Combinatorial Statistic Finder
NIST Digital Library of Mathematical Functions
Google Scholar
Inverse Symbolic Calculator (ISC) – CECM
Inverse Symbolic Calculator (ISC)
JSTOR
MathSciNet (Mathematical Reviews on the Web) – AMS
mathtube.org
MathWorld
Open Problem Garden
MIT OpenCourseWare
Open Yale courses
pastebin.com
PlanetMath
Plouffe's Inverter
www.postimage.org
The Prime Pages
ViewVC
Wolfram|Alpha

Institutes

Pacific Institute for the Mathematical Sciences (PIMS)

seqcomp
The SeqFan Archives

Ask NRICH - the Ask-a-Mathematician service

Stack Exchange

All Sites - Stack Exchange

cs.stackexchange.com
cstheory.stackexchange.com
math.stackexchange.com
mathematica.stackexchange.com
mathoverflow.net
physics.stackexchange.com
scicomp.stackexchange.com
stackoverflow.com
tex.stackexchange.com

Art of Problem Solving
Ask Dr. Math® - The Math Forum @ Drexel
www.physicsforums.com

The n-Category Café
http://whatisresearch.wordpress.com/
http://whatisresearch.wordpress.com/online-math/
http://whatisresearch.wordpress.com/online-math/oeis/
What’s New: Terence Tao’s blog
Mathematics related discussions: Timothy Gowers’s weblog
Combinatorics and more: Gil Kalai’s weblog

Encyclopedia of Mathematics wiki
Incubator (Wikimedia)
GNU Octave Wiki
MathWeb wiki
MediaWiki.org wiki (Wikimedia)
Semantic MediaWiki Community Wiki
Commons (Wikimedia)
Creative Commons Wiki
Wikidata (Wikimedia)
The Open Web Application Security Project (OWASP)
nLab
PolyMath wiki
ProofWiki.org
Qwiki — Quantum physics wiki
Scholarpedia
TorontoMathWiki
Tricki — Tricks (mathematical problem-solving techniques) wiki
UBC Wiki
UBC MathHelp tutoring wiki
Wikipedia (Wikimedia)
Wikibooks (Wikimedia)
Wikimania (Wikimedia)
Wikimania:Hackathon (Wikimedia)
Wikimedia Labs (Wikimedia)
Wikiversity (Wikimedia)

MediaWiki

MediaWiki.el — MediaWiki client for Emacs
mediawikiwiki:API:Main page
mediawikiwiki:API:Client code
Bugzilla — Bug tracker for MediaWiki and its extensions

mediawikiwiki:Scripting

mediawikiwiki:Help:Formatting
List of XML and HTML character entity references
wikipedia:Percent-encoding

Lua scripting

http://www.lua.org/
Lua 5.2 Reference Manual
http://lua-users.org/
mediawikiwiki:Lua scripting
mediawikiwiki:Extension:Scribunto
Test wiki for the Scribunto MediaWiki extension

Javascript

User scripts and Gadgets with JavaScript

OEISF on Facebook
OEIS on Twitter
OEIS on Wikipedia
OEIS on YouTube

Math.OEIS (Haskell)

Math.OEIS
Hackage Dependency Monitor
Math.OEIS needs a new maintainer

Comparison of document markup languages
Mathematical markup languages
Formula editor
http://km-works.eu/mathel-wiki/

MathJax

MathJax
Converting to MathJax from jsMath
The jsMath2jax Preprocessor
Browser Compatibility
MathJax Users Forum

jsMath HTML

jsMath: A Method of Including Mathematics in Web Pages
The tex2math plugin
jsMath Sample Page
Download jsMath (for web-page authors)
How to use jsMath with org-mode

MathML

MathML
Presentation MathML
Content MathML
STIX Fonts
Firemath - The MathML Editor

OpenMath

OpenMath
OMDoc

TeX/LaTeX

http://www.latex-project.org/
http://en.wikibooks.org/wiki/LaTeX
LyX – The Document Processor