What are other good resources on-line for information about TeX, LaTeX and friends?

Newsgroups:

• comp.text.tex: Usenet discussion group for TeX and LaTeX
• de.comp.text.tex: German Usenet discussion group for TeX and LaTeX
• fr.comp.text.tex: French Usenet group
• es.comp.lenguajes.tex: Spanish Usenet group

Web forums:

• TeX, LaTeX and friends on Stack Exchange
• TeXWelt: in German, with format and organization very similar to TeX.SE
• LaTeX-Community.org: LaTeX-dedicated web forum
• goLaTeX Deutsch: German LaTeX forum, with Wiki
• mrunix.de: very frequented German LaTeX subforum of a programmers site
• qa.parsilatex.com: in Persian
• LaTeX.net.br: Brazilian/Portuguese LaTeX web forum and wiki

Frequently Asked Questions (FAQ):

• UK TeX FAQ: FAQ of the UK TeX Users Group, maintained by Robin Fairbairns
• The Visual LaTeX FAQ: formatting samples available through a hyperlink interface
• MacTeX FAQ: Mac OS X specific questions and answers
• AMS FAQ: FAQ for AMS-LaTeX, primarily for AMS authors, but also dealing with amsmath and with LaTeX in general
• de-tex-faq: FAQ of the German TeX user group DANTE e.V.
• Picture FAQ: How to Include Pictures, in German

Software and Package Archives and Catalogues:

• CTAN - The Comprehensive TeX Archive Network: the authoritative collection of materials related to TeX and LaTeX
• The TeX Catalogue Online: TeX/LaTeX package catalogue with topical, hierarchical, brief and alphabetical index
• TeX Resources on the Web: Collection by the TeX User Group
• The LaTeX Font Catalogue: displays nearly all free fonts available for use with LaTeX

Wikis:

• The LaTeX Wiki book on wikibooks.org
• goLaTeX wiki: German wiki with language reference and package information
• LaTeX-Wiki: German wiki

Mailing lists:

• texhax: the original TeX mailing list, going back to the 1980's
• mailing lists of the TeX Users Group: around 50 lists on tug.org for general subjects and certain packages
• mailing lists on gmane.org: among many lists there are several TeX related mailing lists
• ctan-ann - CTAN Announcements: announcements of the Comprehensive TeX Archive Network: updates, new packages etc.
• pgf-users: mailing list for pgf/TikZ
• Typo-L: discussion of type and typographic design
• tex-d-l: German mailing list for TeX and LaTeX

User group sites:

• TUG - TeX Users Group
• UK-TUG: TeX in the United Kingdom
• DANTE e.V.: German users group
• The LaTeX Project
• more groups listed by the TUG
• ParsiLaTeX: Iranian users group

Blogs:

• TeXblog: News and information by Stefan Kottwitz
• Some TeX Developments: blog by LaTeX developer Joseph Wright
• LaTeX Alive: blog by Will Robertson
• LaTeX for Humans: Tips, resources and tutorials
• texblog | because LaTeX matters
• more to be found on texample.net/community

Distributions - where to get a complete TeX system:

• TeX Live: TeX system for Linux, Unix, Mac OS X and Windows
• MiKTeX: user-friendly TeX system for Windows
• proTeXt: easy-to-install distribution for Windows, based on MiKTeX
• MacTeX: TeX Live customized for Mac OS X with useful additions

Editors:

• Cross-platform: Texmaker, TeXstudio, TeXworks, Emacs
• Windows: TeXnicCenter, WinEdt (community), LEd, LaTeX-Editor, WinShell
• Linux: Kile, gedit and plugin
• Mac OS X: TeXShop
• Also see LaTeX Editors/IDEs

Viewers:

• see Output viewers topic for all platforms and formats

Friends: - Software related to TeX and LaTeX

• The ConTeXt Garden
• LyX homepage and wiki
• LuaTeX
• GNU TeXmacs

http://wikibooks.org/wiki/LaTeX

And you can even help improving it yourself :)

The UK TeX FAQ, where you'll the answer to what you're looking for surprisingly often.