TeX

TeXblog - Typography with TeX and LaTeX - Collects useful information about TeX and LaTeX and lists solutions found for often occurring or interesting problems. Further it provides an archive of links regarding TeX and LaTeX.
http://texblog.net/

TeX Resources - A list maintained at U Penn.
http://www.math.upenn.edu/TeX.html

TeX showcase - Examples of professional TeX typesetting of books in the humanities, selected by the Association of American University Presses.
http://www.tsengbooks.com/

Achim Blumensath: Download - Contains manual and source code for Ant which is a typesetting system similar to TeX written in Objective Caml. Various LaTeX packages are also available.
http://www.mathematik.tu-darmstadt.de/~blumensath/Download.html

The TeXability Site - Shows short (mostly single page) documents with immediate access to graphical results and source to demonstrate the power of TeX.
http://texability.corlan.net/

CTAN - The TeX Archive Network is a set of fully-mirrored ftp sites providing the most complete, up-to-date TeX-related software possible.
http://www.ctan.org/

Donald Knuth's Reward Check - An example of a reward check by DEK and how to get one.
http://truetex.com/knuthchk.htm

TeX Merchandising - Merchandising for TeX and friends. On-line ordering with PayPal.
http://www.dream.kn-bremen.de/tex/merchandising/

(La)TeX Navigator - A (La)TeX encyclopaedia from Loria. Also available in French and German.
http://tex.loria.fr/english/

Knuth: Message about TeX Fonts - Important message to all users of TeX.
http://www-cs-faculty.stanford.edu/~knuth/cm.html

Mathematics For Computer Generated Spoken Documents - AsTeR --Audio System For Technical Readings-- is a computing system for rendering technical documents written in LaTeX in audio.
http://www.cs.cornell.edu/info/people/raman/aster/demo.html

The TeX showcase - Edited by Gerben Wierda, it contains examples of what you can do with TeX, from typesetting of scientific papers to music, multimedia, genealogical presentations, dynamic documents, multilingual documents.
http://www.tug.org/texshowcase/

AMS TeX Resources - TeX-related style file collections, fonts, manuals, and author packages for preparing submissions to American Mathematical Society publications. Platforms: PC (DOS and Windows), Macintosh (for Textures, OzTeX or CMacTeX), and Unix.
http://www.ams.org/tex/

Interesting TeX-related URLs - Maintained by TUG.
http://www.tug.org/interest.html

CTAN Search - Online search interface for CTAN. Search CTAN for a file or search the TeX catalogue by Graham Williams for a keyword.
http://www.ctan.org/search/