This growing Directory is manually maintained and periodically tested for broken links.
Should there be anything wrong with an entry, let us know.

INSTITUTIONS, Organizations, Associations and Groups

For a more generic Directory, see the Stan's links to Science Institutions.

• International:
• International Mathematical Union (IMU)
     International Mathematical Congress (ICMI)
     International Commission on Mathematics Instruction (ICMI)
• Mathematics Subject Classification (MSC 2010), is international by impact
• Association for Symbolic Logic (ASL)
• Association for Computing Machinery (ACM).
• Clay Mathematics Institute (CMI) is US, but de-facto International.
• Fields Institute is Canadian but becoming international.
• Gesselschaft für Angewandte Mathematik und Mechanik (GAMM), the
  International Association of Applied Mathematics and Mechanics with German roots.
• Great Internet Mersenne Prime Search (GIMPS). Participate and win money!
• International Association of Mathematical Physics (IAMP)
• International Commission on the History of Mathematics (ICHM)
• International Linear Algebra Society (ILAS)
• International Mathematical Sciences Institutes (IMSI), a large directory by Fields Institute
• International Linear Algebra Society (ILAS)
• International Society for Geometry and Graphics, the (ISGG)
• Research Group in Mathematical Inequalities, (RGMIA), Australian, but becoming international.
• Society for Mathematical Biology (SMB).
• Society of Industrial and Applied Mathematics (SIAM).
• Southeast Asian Mathematical Society (SEAMS).
• Union Matematica de America Latina y el Caribe (UMALCA).
• USA:
• American Institute of Mathematics (AIM).
• American Mathematical Society (AMS). Entry door to MathSciNet.
• Mathematical Association of America (MAA).
• Mathematical Sciences Research Institute (MSRI), Berkeley, California.
• NSF Mathematical Sciences Institutes, a list and an access portal to all of them.
• Association for Women in Mathematics (AWM), with international ambitions.
• Europe:
• European Mathematical Society (EMS). New website!
• European Mathematical Information Service (EMIS).
• mathematics-in-europe.eu.
• European Consortium for Mathematics in Industry (ECMI). New website!
• European Society for Mathematical and Theoretical Biology (ESMTB).
• Austrian Mathematical Society.
• Kurt Gödel Society, Austria.
• Belgian Mathematical Society.
• Bosnian Mathematical Society.
• Union of Bulgarian Mathematicians. See also.
• Hrvatsko matematičko društvo, Croatia.
• Union of Czech Mathematicians and Physicists.
• Institute of Mathematics of the Czech Academy of Sciences, Czech.
• Dansk Matematisk Forening, Denmark.
• Association des Collaborateurs de Nicolas Bourbaki, France.
• Société Mathématique de France.
• Deutsche Mathematiker Vereinigung (DMV), Germany.
• Mathematische Gesselschaft in Hamburg, Germany.
• Mathematisches Forschungsinstitut Oberwolfach (MFO), Germany.
• Hellenic Matematical Society, Greece.
• János Bolyai Matematical Society, Hungary.
• Irish Matematical Society.
• Unione Matematica Italiana. Italy.
• Luxemburg Matematical Society (SML).
• Koninklijk Wiskundig Genootschap, Netherlands.
• Norsk Matematisk Forening, Norway.
• Institute of Mathematics of the Polish Academy of Science, Poland.
• Sociedade Portuguesa de Matemática (SPM). Portugal.
• Societatea de Stiinte Matematice din Romania. Romania.
• Societatea Româna de Matematica Aplicata si Industriala (ROMAI). Romania.
• Union of Slovak Mathematicians and Physicists. Slovakia.
• Društvo matematikov, fizikov in astronomov. Slovenia.
• Real Sociedad Mathemática Española, Spain.
• Societat Catalana de Matemàtiques, Spain.
• Sociedad Española de Mathemática Aplicada (SeMA), Spain.
• Svenska matematikersamfundet (SMS). Sweden.
• The Swiss Mathematical Society (SMS). Switzerland.
• Institute of Mathematics & its Applications (IMA), UK.
• London Mathematical Society (LMS), UK.
• Isaac Newton Institute for Mathematical Sciences in Cambridge, UK.
• The Scottish Mathematical Council (SMC), Scottland, UK.
• Elsewhere:
• African Institute for Mathematical Sciences, AIMS, Africa, Tanzania.
• Unión Matemática Argentina, UMA, Argentina.
• Australian Mathematical Society, AustMS, Australia.
• Statistical Society of Australia SSA, Australia.
• Belarussian Mathematical Society, Minsk, Belarus.
• Sociedade Brasileira de Matemática (SBM). Brazil.
• Cambodian Mathematical Society, Cambodia.
• Canadian Mathematical Society, CMS, Canada.
• Canadian Applied and Industrial Mathematics Society, CAIMS, Canada.
• Pacific Institute for the Mathematical Sciences PIMS, Vancouver, Canada.
• Sociedad de Matemática de Chile. Chile.
• WuHan Institute of Physics and Mathematics of the Chinese Academy of Sciences. En. China.
• The Hong Kong Mathematical Society, China.
• The Mathematical Society of the Republic of China, China (Taiwan).
• Sociedad Colombiana de Matemáticas, Colombia.
• Bhaskaracharya Institute of Mathematics in Pune, India.
• School of Mathematics of the Tata Institute of Fundamental Research, India.
• The Institute of Mathematical Sciences in Chennai, India.
• Israel Matematical Union, Israel.
• Technion math website. Haifa, Israel.
• Japan Society for Symbolic and Algebraic Computation.
• Research Institute for Mathematical Sciences in Kyoto, Japan.
• Korean Mathematical Society. Korea.
• Malaysian Mathematical Society. Malaysia.
• Sociedad Matemática Mexicana. Mexico.
• Myanmar Mathematical Society. Myanmar.
• New Zealand Mathematical Society. New Zealand.
• Pakistan Mathematical Society. Pakistan.
• Sociedad Matemática Peruana. Peru.
• Mathematical Society of the Philippines. Philippines.
• Math-Net.Ru, the All-Russian Mathematical Portal, Russia.
     Moskow Mathematical Society
• Sobolev Institute of Mathematics of the Russian Academy of Sciences, Novosibirsk, Russia.
• St. Petersburg Mathematical Society, Russia.
• Steklov Mathematical Institute of the Russian Academy of Sciences, Russia.
• Singapore Mathematical Society, IMS, Singapore.
• Institute for Mathematical Sciences, IMS, Singapore.
• South African Mathematical Society.
• Mathematics Foundation of Turkey. Turkey.
• Türk Matematik Dernegi. Turkey.
• Kharkov Mathematical Society, Ukraine.
• Ukrainian Mathematical Community, Ukraine.
• Ukrainian Mathematical Society, Ukraine.
• Sociedad Uruguaya de Matemática y Estadística (SUME). Uruguay.
• Vietnam Mathematical Society (VMS). Vietnam.

JOURNALS, Libraries, e-Zines and Forums, Blogs

• ArXive Math is an open-access repository for papers. Try arXive front-page for easy access.
• AMS Journals. A complete list of AMS Journals, with links.
• MathSciNet. An AMS mathematical publications search engine..
• Biometrika. This Journal covers most of applied statistics (the name is a bit too narrow).
  UK graduent students working for a Statistics PhD get a free subscription.
• Czech Digital Mathematics Library offers open access to over a dozen math journals like Czechoslovak Mathematical Journal, Applications of Mathematics, etc
  Many are in English, some are in Czech.
• European Digital Mathematics Library (EUDML).
• Electronic Library of Mathematics (ELibM) on FIZ Karlsruhe / Zentralblatt MATM (zbMATH).
• Journal of Humanistic Mathematics.
• Journal of Integer Sequences. Founded by N.J.A.Sloane.
• Math journals. A global journals directory endorsed by AMS.
• Open Access Mathematics Journals. Look at Science|Mathematics:
  The last Journals/Articles count: 121031. The listed Journals are 555.
• Real Analysis Exchange. A Journal which also organizes international Summer Symposia.
• Stan's Library section on mathematics. Open Access.
• Theory and Applications of Categories. Open access.
• World Digital Mathematics Library (WDML) discussed by IMU .
• e-Zines and Forums
• Chance News, part of a probability project at Dartmouth.
• Math Central at Uni Regina, Canada.
• Math Forum @ Drexel is crammed with resources and links.
• Math Forum Website on MAA. It defaults on the above Math Forum @ Drexel for discussions.
• Math Overflow, a Question and Answer site for professional mathematicians.
• Mathematics at About.com.
• Mathematics on Stackexchange.
• Planet Math is a virtual community and a vast Forum.
• Plus Magazine ... living mathematics e-zine.
• Science4All. An educational e-Zine run by by Lê Nguyên Hoang. In English and French.
• Scientific Computing World magazine.
• Topology Atlas, a forum related to topology. Now closed but its archive is still online.
• Blogs:
• Annoying Precision of Qiaochu Yuan is very edu-friendly.
• Abstract math of Charles Wells.
• AMS Blogs. Ten top-quality blogs hosted by AMS.
• Ars Mathematica. Dedicated to the mathematical arts. Vague title, good contents.
• Azimuth of John Carlos Baez. This is not about Math, it is Physics and ++, too. Very good :-)
• Blog on Math Blogs on AMS.
• Combinatorics and more of Gil Kalai.
• Devlin's Angle of Keith Devlin (associated with MAA).
• Division by Zero of Dave Richeson.
• dy/dan of Dan Meyer.
• e-Mentoring Network, edited by Ricardo Cortez and Dagan Karp.
• Gowers's Weblog of Timothy Gowers.
• Math Blog, started by Antonio Cangiano, but expanding.
• Mathematics Journals of John Ewing. Reflections about scientific publishing.
• Nathaniel Johnston's blog. Lots of Math but be warned: he is into quantum computing :)
• NeverEndingBooks of Lieven le Bruyn. Great full-length articles. See also
• Not Even Wrong by Peter Woit is more about mathematical physics.
• Pankaj Jyoti Mahanta's blog is great, especially if you can read Assamese.
• Rigorous Trivialities of Charles Siegel is very educational.
• Secret Blogging Seminar by a motley crew of recent Berkeley Ph.D. students.
• Statistical Modeling, Causal Inference, and Social Science of Andrew Gelman + others.
• Tanya Khovanova's Math Blog.
• The n-Category Café, a group blog on math, physics and philosophy.
• The Spectre of Math of Jiri Lebl.
• Shtetl-Optimized of Scott Aaronson is into complexity, computer learning, quantum computing, ...
• The Unapologetic Mathematician.
• Visual Insight. Striking images that help explain advanced topics. Edited by John Baez.
• What's new of Terence Tao is rather advanced.
• Wild about Math!

ENCYCLOPEDIAs and Dictionaries, Wikis

• Encyclopedia of Mathematics under imprimatur of European Mathematical Society and Springer.
• Mathematics Dictionary & Glossary for students at ITS.
• Mathwords. A simple illustrated Math dictionary. Good basic level education.
• MathWorld site of Eric Weisstein. It became an Institution! Selected pages:
     Constants of Mathematics
     Numbers: Natural, Integer, Rational, Real, Complex, Quaternions, Octonions
     Real numbers: Irrational, Algebraic, Transcendental,
     Unsolved problems
• Mauro Fiorentini is bulding what resembles MathWorld, but in Italian. Selected pages:
     Congetture, Funzioni, Problemi
• The On-Line Encyclopedia of Integer Sequences (OEIS, ex Sloane's)
• Math Wikis and similar resources:
• Wikipedia Mathematics. Selected pages:
     Mathematics and Mathematics Articles on Wikipedia
     List of unsolved problems in mathematics and Millennium Prize problems
     Mathematical constant and the list of Mathematical constants and functions
     Beal's conjecture
     MathML and LaTex
• Chance Wiki is part of a project in probability.
• Complexity Zoo is a Wiki deticated to ... well, complexity. Uni Waterloo (Canada).
• Dispersive PDE Wiki is of interest to mathematical physicists.
• Math Structures is into algebraic spaces and the like.
• Math Wiki on Wikia.
• Mathematics on Wikibooks. Interesting
• Mathematics definitions Wiki on Wiktionary
• Mathematics quotes Wiki on Wikiquote
• Mathematics Subject Classification Wiki on MSC 2010
• Mersenne Wiki for those who are into primes, GIMPS, etc.
• PolyMath projects Wiki
• OEIS Wiki on The On-Line Encyclopedia of Integer Sequences

Mathematics HISTORY

• Mathematics History: AMS Books and Resources. A treasure trove.
• Classical Works, Selecta, and Opera Omnia on EMIS.
  Online collected math papers of W.R.Hamilton, G.F.B.Riemann, and P.Erdös.
• Historical Math Monographs at Cornell University Library.
• International Commission on the History of Mathematics (ICHM).
• Mathematics Genealogy Project at North Dakota State University.
• Abacus, the art of calculating with beads and its history. By Luis Fernandes (elf).
• Jeff Miller Web Pages, a nice project. See in particular:
     Earliest Known Uses of Some of the Words of Mathematics
     Earliest Uses of Various Mathematical Symbols
     Earliest Uses of Various Mathematical Symbols
     Images of Mathematicians on Postage Stamps
• History of Approximation Theory on Technion math website.
• History of Mathematics pages on the website of David E. Joyce. See in particular:
     The Mathematical Problems of David Hilbert, including an HTML version of Hilbert's address
     History of Mathematics by subject
     Books and other nonweb resources
     Chronological list of Mathematicians
• The Erdös Number Project. Both history and a modern initiative.
• Gauss's second proof of the fundamental theorem of algebra,
  translated from Latin by Paul Taylor.
• Vedic Mathematics. I did not know where to put this: history or education? So I put it in both.

PIONEERS of Mathematics

• MacTutor History of Mathematics archive at St.Andrew's University. Excellent beyond belief!
• Mathematician of the day on the above website. This is fun.
• Portrait Gallery of Mathematicians A-M and N-Z at MAA.

Mathematics PRIZES and unsolved PROBLEMS

• Abel Prize is much like a Nobel for Math. See also About the Abel Prize. Some laureates:
  2016: Sir Andrew J. Wiles; proof of Fermat's Last Theorem.
  2015: John F. Nash, Jr. and Louis Nirenberg; new PDE's theory and applications, ...
  2014: Yakov G. Sinai; math physics, dynamical systems, ergodic theory, ...
  2013: Pierre Deligne; algebraic geometry, number theory, ...
  2012: Endre Szemerédi; discrete math, computer science, ...
  2011: John Milnor; topology, geometry, algebra, ...
  2010: John Torrence Tate; number theory.
• IMU Prizes and Medals, awarded by the International Mathematical Union every 4 years
  (click here for recent laureates):
     Fields Medal, the highest Math award for young people
     Rolf Nevanlinna Prize, for computer science math
     Gauss Prize, for applied mathematics
     Chern Medal, for achievements that boost public recognition of mathematics
• CMR-Fields-PIMS Medal by the Canadian institutes.
• GIMPS awards for new Mersenne primes, and for record ones with 10^8 and 10^9 digits.
  The latter are offered by Electronic Frontier Foundation (EFF).
• Famous Unsolved Math Problems (the tip of the iceberg)
• Hilbert's Problems, the famous lecture Hilbert delivered before the International Congress of Mathematicians in Paris in 1900. Only three of the problems (8, 12 and 16) are still unsolved and undisputed. See also Wikipedia and MathWorld.
• Millennium Problems. Seven problems selected by the Clay Mathematics Institute.
  Each carries a $1M award. One was solved (Poincaré Conjecture). See also Wikipedia.
• Beal Conjecture, with a prize of $1'000'000.
  Related links: Wikipedia, MathWorld, AMS article
• Goldbach Conjecture used to carry a prize by Francis & Taylor, but it is off now.
  Related links: MathWorld, Fiorentini's
• Lists of unsolved math problems on: MathWorld, Wikipedia, Fiorentini's
• The funny side

RESOURCES: Large DataBases + Links & Lists

• ACM Digital Library Portal.
• MathSciNet. An AMS searchable mathematical publications database.
• European Mathematical Information Service (EMIS). Lots of solid open access stuff.
• European Digital Mathematics Library (EUDML).
• MathDL, a Digital Library initiative of MAA. No longer supported :-(
• CERN Document Server, an open-access repository of articles, theses, ... Search for mathematics.
• Computing Pi: Lists of Machin-type (inverse cotangent) identities for Pi/4, maintained by M.R.Wetherfield & H.Chien-lih.
• Czech Digital Mathematics Library. Open access to many Journals, Proceedings, Collections, and Books. Many are in English, but just as many are in Czech.
• Handbook of Mathematical Functions edited by M.Abramowitz, A.Stegun.
  A printed handbook that became an online reference.
• IEEE 754, the official 2008 floating-point standard.
• IEEE 754 Standard: The floating point format. Notice the Reading material.
• Interactive Mathematics maintained by Murray Bourne.
• MathCS, maintained by Bert G. Wachsmuth, is a huge math resource.
• Mathigon World of Mathematics created by Philipp Legner is the most beautiful website
  I have ever seen and a vast resource. Great job, Philipp.
• Mathematics Books, a huge reference list with Amazon links. Maintained by Stan Sykora.
• Mathematics Bookshelf on Project Gutenberg. Great and Free!
• Mathematical Constants by Steven Finch, plus a lot more. Many PDF's. Excellent.
• Mathematical Constants and Sequences, edited by Stan Sykora.
• Mathematics Subject Classification, MSC 2010, from AMS.
• National Curve Bank. Managed by Shirley Gray, Stewart Venit, and Russ Abbott.
  There are famous curves and much more.
• NIST. National Institute of Standards and Technology. Some relevant sub-sections:
     NIST Math. The main Math portal.
     DADS. Dictionary of Algorithms and Data Structures.
     DLMF. Digital Library of Mathematical Functions.
     Engineering Statistics, an online handbook.
     Gallery of Distributions. Common statistical distributions, with links.
• Numbers Aplenty of Giovanni Resta.
• Platonic Solids and all things polyhedral, maintained by Dan Radin.
• Random: Probability, Mathematical Statistics, Stochastic Processes.
  A huge, high quality online project, covering most of Statistics. More than a book.
• Reprints in Theory and Applications of Categories. A collection of 25 (so far)
  open-access online books and/or large articles. Some were originally publisshed as books.
• The Prime Pages maintained by Chris Caldwell.
• Think Zone posters/charts by Keith Enevoldsen.
• VassarStats: Website for Statistical Computation, free resource maintained by Richard Lowry.
• Tetration website of Daniel Geisler.
• The World of Mathematical Equations on EqWorld, the English version of a Russian site.
• Wavelets.org - all there is to know about them. Great resource!
• Web Primes, a huge online repository of prime numbers and related stuff.
• LINK DIRECTORIES and additional RESOURCES (many can be downloaded)
• AMS Books Online. Many are free or, in some cases, there are open-access Chapters.
• Geometry, a collection of articles and links.
• Historical Math Monographs at Cornell University Library. Excellent open-access resource.
• Imathination. Lots of funny and useful stuff. Great links.
• List of Mathematics Pages at Textbook Revolution
• Math Archives: Topics in Mathematics. A great resource (Uni Tennessee).
• Math Courses from the MIT Open CourseWare initiative. Great.
• Math on the Web. A very large directory. Must see.
• Mathematics on Wikibooks. Interesting.
• Mathematics Online Texts. Links to free books, theses and courses maintained by Stan Sykora.
• Number Theory Web maintained by Keith Matthews.
• Numbers, constants and computation of Xavier Gourdon and Pascal Sebah. 223 titled references.
• Numericana of Gérard P. Michon. A rich source of information from magnificient to the obscure.
  For example, see Numerical Constants.
• Online mathematics books on FreeScience. It includes courses and lectures.
• Online mathematics books on eKnigu. Hundreds of items in PDF and DjVu fomats
• Online Mathematics Textbooks, links collected by George Cain.
• Publications of the Mathematical Sciences Research Institute. Thematic collections.
• Publications of the School of Mathematics at Tata Institute of Fundamental Research.
• Publishing House of the European Mathematical Society. Commercial books.
• Stan's Library section on mathematics.
• StatsToDo. Over 200 articles about Statistics. Practical, informative, free.
• Theory and Applications of Categories open-access Journal. See also the TAC Reprints.
• Trillia Group online Math, a collection of free lecture notes and references (ex Stefanov's list)
• Virtual Math Library at University of Florida. Very useful.
• Webring of Mathematics.

PERSONAL WEBSITES and websites run by individuals, usually crammed with free resources

NOTE: All the mathematicians in the World must be about 10⁶ times as many as those listed here. So the latter are just those I happened to hit upon while browsing the Net, starting not a long time ago. If you are not here and, having something to share with others, you would like to be listed, let me know.

• Scott Aaronson. Complexity, AI, quantum computing, ... Runs Shtetl-Optimized.
• Jiri Adamek. Algebraic categories.
• Jörg Arndt's useful and ugly pages.
• Semjon Adlaj. Introduced clever uses of modified AGM (see Articles).
• Sam Alexander runs Xamuel.com.
  Highlights: the Inverse Graphing Calculator and the Patterns of Resemblance software.
• Late Robert B. Ash website. Nine free books and courses.
• John Baez. A mathematical physicist with an infinite-depth website.
• Stefan Bilaniuk, apart from serious work, has some nice Odds and Ends.
• Paul Bourke. See his Geometry, Surfaces, Curves, Polyhedra, Fractals, ....
• Murray Bourne maintains Interactive Mathematics.
• Stephen P. Boyde. Convex optimization, control theory, applied math, ....
• George Cain is into topology.
• Chris Caldwell maintains The Prime Pages.
• Predrag Cvitanovic' likes group theory and chaos. He is more a physicist.
• Reinhard Diestel likes graph theory.
• Andrew Gelman co-runs the blog Statistical Modeling, Causal Inference, and Social Science.
• Robert M. Gray. Statistics, information, entropy. A list of free books.
• W. Timothy Gowers runs the Gowers's Weblog. See also.
• Bill Casselman wrote Mathematical Illustrations.
• Zev Chonoles. I love his collection of links.
• Henri Cohen is into number theory, computations, ...
• Jonathan Crabtree likes math recreations and history.
• Ronald DeVore. PDE's, algorithms, ...
• Andreas Dieckmann. Math, physics, electronics. Tables of infinite products and of integrals.
• Keith Enevoldsen runs the Think Zone.
• David Eppstein. I love his Geometry in Action.
• Steven Finch started with the Math Constants and then went a long distance.
• Mauro Fiorentini is building a kind of Italian MathWorld. Over 1383 entries.
• Erich Friedman. Education + much more.
• Jean Gallier. Logic, computer science, discrete math. Look at his books in progress
• Daniel Geisler runs Tetration.
• Xavier Gourdon & Pascal Sebah. Numbers, constants and computation.
• Evans Harrell. Linear Methods of Applied Mathematics, plus more.
• Allen Hatcher. Algebraic topology resources.
• Jim Hefferon. Useful linear algebra and number theory texts.
• Lê Nguyên Hoang runs Science4All.
• Fredrik Johansson is behind the C-library Arb.
• David E. Joyce. Education, math history, and more.
• Gil Kalai does geometric combinatorics and runs the blog Combinatorics and more.
• David King's homepage is empty, but his Hall of Hexagons is great.
• Ron Knott. Archived pages for those who want maths with fun and who like to play with numbers.
• Lieven le Bruyn. The Belgian who does abstract algebra and runs NeverEndingBooks. See also
• Jiri Lebl. Wearer of hats, with a lot of math under them.
• Bradley Lucier. Wavelets, PDE's, lots of software, ...
• Late Joseph F. MacDonnell, with a nice treatement of the hyperpower function.
• Pankaj Jyoti Mahanta. Co-author of Gonit Sora (with Manjil Saikia).
• Andrei Marcus. Well organized website with abundant resources.
• Michael B. Marcus. Stochastic processes, plus more.
• Keith Matthews maintains the Number Theory Web.
• R. Daniel Mauldin. Analysis, probability, set theory, chaos, ... Great list of papers.
• J. Peter May. A great topology resource with many online texts.
• Gérard P. Michon runs Numericana. Lots of information from magnificient to the obscure.
• James Milne. Elliptic curves, groups, fields, cohomology, ...
• Robert Munafo. Eclectic, very interesting ... Must see!
• Hans D. Mittelmann. A treasure on numerical optimization methods.
• Gergo Nemes likes asymptotic approximations, but not only.
• Richard Palais maintains Virtual Math Museum.
• Cliff Pickover, an amusing and inspiring site of a popular author.
• Karlis Podnieks. Very nice reflections.
• Carl Pomerance. Number theory, prime numbers, ...
• Dan Radin is a Platonic Solids fan.
• Giovanni Resta maintains Numbers Aplenty and other math fun pages.
• Dave Richeson runs the nice blog Division by Zero.
• Jeffrey S. Rosenthal. Statistics, Markov chains, ...
• Manjil Saikia. Co-author of Gonit Sora (with Pankaj Jyoti Mahanta), an Indian in Austria.
• Christopher J. Sangwin. Nice educational stuff.
• Eric Schechter. He says he is retired, full stop. But this page links to mountains of goodies.
• Paul Seeburger created CalcPlot3D.
• Victor Shoup does number theory and maintains the NTL Library.
• Neil J. A. Sloane. The grandfather of OEIS.
• Elena Smirnova, MathML +more.
• Shlomo Sternberg. Professor at Harvard. Course materials for Analysis and Geometry, books.
• Ian Stewart. Mathematician, science writer, science fiction writer.
• Stanislav Sykora runs Stans Hub. Physicist trying to dab in Math.
• Terence Tao runs What's New. See also.
• Late Albert Tarantola. This site continues to be a first class educational resource.
• Paul Taylor. Interesting stuff and many resources.
• Gerald Teschl. Spectral theory for differential/difference operators. Lots of resources.
• Peter Valkó. Numerical inverse Laplace transform methods +more.
• Bert G. Wachsmuth is behind MathCS, a huge resource.
• Eric Weisstein is behind MathWorld.
• Charles Wells has an Abstract Math website.
• Late Herbert S. Wilf's website still carries resources in algorithms, complexity, ...
• Peter Woit. Quantum mechanics, Lie groups. He runs Not Even Wrong.
• Xuru. I have no idea who is Xuru, but his website is nice. Mostly statistics.
• Doron Zeilberger. His website is a "must follow". Do not miss his Dr.Z's Opinions.

EDUCATION + Fun

• List of free online mathematics books, courses and theses
• Ambiguously Defined Mathematical Terms at the High School Level,
  a useful web page of Jeff Miller Web Pages.
• Art of Problem Solving for students and their parents and teachers.
• CAUSE, Consortium for the Advancement of Undergraduate Statistics Education.
• Convergence. An MAA magazine where mathematics, history and teaching meet.
• Gonit Sora - Enter the fascinating world of mathematics. Assamese & English.
• Had to know. An edu resource to bookmark.
• Hosting Online Math Resources for Kids:
  a links collection recommended by a young student (tx, Chris).
• Khan Academy, open-source videos and lessons. See also.
• KryssTal mathematics section. Nice!
• MATH-abundance. An abundance of math tutorials, indeed.
• Math and Reading Help for Kids, a nice directory of math-education articles, games, etc.
• Math e Book, or Learn Math Online.
  Nice and free resource for math teachers & students (from Kindergarden to HS).
• Math on About.com. Focused on math education.
• Maths online, a Gallery of Java applets, puzzles, tests, and tools, plus much more.
  Maintained by Franz Embacher and Petra Obenheumer. Also im Deutch (more complete).
• Math Planet, lectures and free short videos for kids.
• Math Playground, lots of stuff for kids aged 5-14.
• Math Courses from the MIT Open CourseWare initiative. Great.
• MERLOT. An amazing educational resource.
• Online Statistics Education. A free, interactive multimedia course of study from Rice University.
  See also the Rice Virtual Lab in Statistics.
• Science4All. An educational e-Zine run by by Lê Nguyên Hoang. In English and French.
• Space Math @ NASA. With problems to solve and much more!
• Stan's Library educational math Section.
• Think Zone of Keith Enevoldsen has lots of edu stuff.
• Vedic Mathematics. I did not know where to put this: history or education? So I put it in both.
• Fun:
• A simple solution to the Monty Hall problem, by Jeffrey S. Rosenthal.
• Amusements in Mathematics, a open-access book by Henry E. Dudeney.
• Astounding Math Stories by Charles Wells.
• Books by Ian Stewart, available on Amazon:
  - Game, Set and Math: Enigmas and Conundrums
  - Why Beauty Is Truth: A History of Symmetry
  - How to Cut a Cake: And Other Mathematical Conundrums
  - Math Hysteria: Fun and Games with Mathematics
  - The Science of Discworld I,
  - The Science of Discworld II: The Globe,
  - The Science of Discworld III: Darwin's Watch
  - Another Fine Math You've Got Me Into ...
  - Nature's Numbers: The Unreal Reality Of Mathematics
  - Does God Play Dice? The New Mathematics of Chaos
  - From here to Infinity
  - Letters to a Young Mathematician (Art of Mentoring)
• Fun Facts at Harvey Mudd College. Excellent!
• Fun with Formulas on KryssTal. Cute.
• Inverse Graphing Calculator on the website of Sam Alexander. This is cute :)
• Math humor at Uni Utah.
• Math jokes on the website of Zev Chonoles.
• Mathematicians jokes at WorkJoke.
• Math puzzles collected by David E. Joyce:
  - Dave's Square Dissection puzzles,
  - Dudeney's Catching the Mice puzzle,
  - Shasha's Surprizing Strings puzzle,
  - Hickerson's Prime Maze puzzle.
• Mathematical Art at the Virtual Math Museum. Amazing.
• Mathematics and Sex, a book by Clio Cresswell. It is sure worth the $10.
• Robert Munafo's math-recreations:
     Large Numbers
     Mu-Ency - The Encyclopedia of the Mandelbrot Set
     Notable Properties of Specific Numbers
     Some Integer Sequences
• Next Assignment letter by Archangel Gabriel has to do with the number π.
• Numbers Aplenty and other webpages by Giovanni Resta. Amusing online calculations.
• Platonic Solids site of Dan Radin. It even includes a Platonic Solid Rock video.
• Recreational Math, collected and/or created by David Eppstein.
  Recommended: the Geometry Junkyard.
• Ron Knott's web pages on Mathematics.
  Recreation with Fibonacci's numbers, Egyption fractions, Pythagorean triangles, ...
• Some Math Quotes collected by Stefan Bilaniuk (see all his Odds and Ends :)
• Sheppard software. They make learning fun. Online games!
• Theorem of the day. Great, though some think that theorems are no fun.
• What's Special About This Number? by Erich Friedman. Covers the first 1000 integers.
• XKCD comics!

SOFTWARE

• Free, open source, and very low-cost:
• Arb, an arbitrary precision C library maintained by Fredrik Johansson.
• FXT library and much more.
• GNU Free Software Directory, free, serious, official, GREAT.
• GMP (GNU Multiple Precision Arithmetic Library), a free resource for arbitrary precision math.
• GNU C library master sources.
• GSL (GNU Scientific Library) for C and C++ programmers.
    - GSL binding for R
    - GSL binding for Python.
    - GSL binding for Lisp.
• Java Applets on Mathematics. Multilingual resource from Walter Fendt.
• Java on MathCS. Programming, source code, tutorials, ...
• High-Precision Software Directory. Legacy packages website.
     Hosts MPFUN2015, MPFUN90, ARPREC, QD.
• Maple Packages and Programs from Doron Zeilberger.
• Math.Net, an open source initiative to provide numerical computation methods and algorithms.
• MPFR (Multiple Precision Floating-Point Reliably). A nice open project based in France.
• MPC, a superstructure of MPFR for complex numbers.
• Netlib Repository of mathematical software, papers, and databases.
• NTL: A Library for doing Number Theory by Victor Shoup.
• Octave. A numerical computations package and an interpreted language. Free GNU project.
• PARI/GP, a great arbitrary precision C++ library for numeric math research.
     It does also symbolic computing, and comes with a console calculator (GP).
     Related: PARI/GP tutorial by Robert B. Ash.
• R Project. Free environment for statistical computing. Runs in Unix, Windows, MacOS.
• RIES. the Inverse Equation Solver from Robert Munafo. Cute.
• SAGE, a free mathematics software system licensed under the GPL. Uses Python.
• SCILAB, a free and good competitor of MATLAB.
• Runiter Company software packages. Very affordable, very useful.
• Ultra Fractal. Nice, has a 30 days demo.
• VassarStats: Website for Statistical Computation, free resource maintained by Richard Lowry.
• Related to LaTeX:
• LaTeX Editor. Free LaTex editor & IDE for Windows distributed by Brothersoft.
• TtH converts LaTeX to HTML. Seems to be great and free.
  It does NOT translate to MathML; the result is native HTML with no use of images etc.
• WinShell for LaTeX,a free multilingual IDE for LaTeX and TeX.
  An independent LaTeX package is still required. Word to LaTeX converter also available.
• Word2TeX; shareware, low-cost Word (doc) to LaTeX converter.
  The reverse (TeX2Word) is also available.
• Writer2LaTeX sourceforge project. Great. Converts OpenOffice and LibreOffice docs to LaTeX.
  Also available: Writer2xhtml and Writer4LaTeX OpenOffice/LibreOffice extensions!
• LaTeX projector class, an online manual for preparing slides.
• Related to MathML and MathJax:
• MathJax, a universal open-source JavaScript display engine for mathematics.
• W3C MathML. Home of the Math Markup Language. See The Fundamentals.
• MathML on Wikipedia.
• MathPlayer at Design Science. Plugin for Internet Explorer to read MathML. Free.
• MathML test page (one of many).
• MathML stuff on thee website of Elena Smirnova.
• Commercial software of some weight:
• HASKELL. A major computational algebra system. Expensive.
• MAGMA. A major computational algebra system.
• MAPLE. They have several products to do Math, be it symbolic or not.
• Mathematica from Wolfram. A symbolic-math jewel. Related links:
     WolframAlpha. Free, online symbolic math utility.
     Essential Mathematica for Students of Science by James J.Kelly.
• MathType home at Design Science. Professional version of Microsoft's Equation Editor. Affordable.
• MATLAB home at MathWorks.
• PTC Mathcad.
• Multiphysics home at Comsol.

MATH TOOLS: Calculators, Utilities, Online utilities

• AP Statistics, an App on iTunes (Apple).
• Calc98, good multi-mode calculator.
  There is also a reduced-functionality online version (jCalc).
• Calculate for free, large set of online calculators and a functions graphing tool.
• CalcPlot3D, a Java applet from Paul Seeburger, supported by NSF and recommended by MAA.
• Calculator++ on ILOC.com: cross-platform (Java), arbitrary precision.
• Calculators on Had to Know.
• Deadline, a simple function grapher.
• Derivative Calculator from David Scherfgen. Online symbolic derivatives. Nice.
• Googol+ from Atelier Web is great if you need an arbitrary precision calculator.
• GraphCalc, nice graphing calculator from a SourceForge project. Source code available.
• Graph paper. Various formats, including Smith charts.
• Graph paper. More formats; very useful.
• Inverse Symbolic Calculator. Ex Plouffe's, but quite different today.
• Maths online, a Gallery of Java applets, tools, and more. See Online tools.
• MathStudio, low-cost graphing and symbolic math App for mobiles and Windows.
• MVT, Mathematical Visualization Toolkit from Uni Colorado. Usable also online.
• Pre-Calculus, an App on iTunes (Apple).
• StatDistributions.com, an online calculator for Normal, Student's t, χ², and F-distributions.
  By Nathaniel Johnston.
• Xuru's website includes online regression and statistical tools.

SPECIAL Topics: just what I looked at recently

• Math instruments:
• Abacus, the art of calculating with beads. By Luis Fernandes (elf).
• Eric's Slide Rule Site of Eric Marcotte.
• Slide rules and other mathematical instruments. An article by Christopher J. Sangwin.
• Wavelets:
• Wavelets.org - all there is to know about them. Great resource!
• Wavelets, a 50-page paper (almost a book) by Ronald DeVore and Bradley Lucier.
• Graph theory:
• Math 103 by Larry Bowen. First two Sections.

Online ARTICLES: just what I looked at recently

• The Collatz Conjecture as a Fractal, on Nathaniel Johnston's blog.
• An Eloquent Formula for the Perimeter of an Ellipse by Semjon Adlaj. Uses AGM.
• Math + Religion = Trouble, an article by Ron Csillag.
• Paul Erdös bio an article by Joshua Hill.
• What does "DOING MATH" mean? an article by Keith Devlin.
• Articles by Andreas Dieckmann:
     On Surface Area Of An Ellipsoid
     Amplitude and Phase of a discrete Fourier Spectrum
     Collection of Infinite Products and Series. WOW!
     Table of Integrals. Indefinite ones. WOW!
     Table of Integrals. Definite ones. WOW!
• The number of direct-sum decompositions of a finite vector space
  by David Ellerman.
• Articles by Lê Nguyên Hoang on Science4All:
     Hypothesis Test with Statistics: Get it Right! on Science4All.
• Maximum polygon area on David King's Hall of Hexagons.
• A Generalization of Fermat's Last Theorem: The Beal Conjecture and Prize Problem
  by R. Daniel Mauldin.
• The continuum hypothesis by Nancy McGough. Very incomplete.
• The 15 Most Famous Transcendental Numbers by Cliff Pickover.
• Harold Jeffrey's Theory of Probability Revisited, by Christian P. Robert, Nicolas Chopin and Rousseau Judith.
• A simple solution to the Monty Hall problem, by Jeffrey S. Rosenthal.
• A MathML example, by Elena Smirnova.
• Articles by the late Prof. Albert Tarantola:
     Popper, Bayes and the Inverse Problem,
     Probabilistic Approach to Inverse Problems (with Klaus Mosegaard)
     Mathematical Basis for Physical Inference (with Klaus Mosegaard)
     Monte Carlo Sampling of Solutions to Inverse Problems (with Klaus Mosegaard)
     Generalized Nonlinear Inverse Problems Solved using the Least Squares Criterion (with B.Valette)
     Three-Dimensional Inversion Without Blocks (with Alexandre Nercessian)
     Noninformative Probability Density for the Elastic Tensor
     and much more ...
• Articles by Stan Sykora (my own, sorry).

SANDBOX: for temporaries and/or items yet to be sorted

• Meta-Calculator, online sci, graphing, stat, and 3x3 matrix calculators.
• The birthday problem.
• The 100 Greatest Theorems. Good idea, but left incomplete.