Desktop
- Fences - group and show/hide desktop icons
- hott notes - sticky notes
- ObjectDock - emulate the Dock from Mac OS X
- Rainmeter - compact CPU / RAM / network / disk space monitor
- Rainlendar - compact calendar - link it to Google Calendar with GCALDaemon
- VirtuaWin - virtual desktops
- Yahoo! Widgets - eye-candy weather widget
Utilities
- FreeMind - mind map creator
- gVim - 'vi' text editor
- Hack-It - control hidden windows
- PuTTY Tray - URL-aware SSH client
- TortoiseSVN - Subversion client interface integrated into Explorer
Browsers
E-mail, Usenet, RSS
Instant messaging / social networking
- Pidgin - single interface to multiple IM services
- Twitter - multi-cast IM
- tweet.im - Twitter to/from IM
- TweetDeck - standalone Twitter client with groups
- LiveJournal - personal blogging
- LoudTwitter or Twittinesis - Twitter to LiveJournal (lj-cut or style adjustment recommended if you tweet many times a day)
- LiveJournal Archive
- Facebook - find your old friends without evil sign-up fees
- Twitter to Facebook / Facebook to Twitter (don't use both!)
- Facebook plugin for Pidgin
Online roleplay
- SimpleMU (alternate download location)
- MUSHclient
- TinyFugue (text)
- Atlantis (OS X)
Firefox add-ons
- AdBlock Plus
- Image Zoom
- Open in Browser - override MIME type
- PDF Download
- CoolIris aka PicLens - eye candy
- Smart Middle Click - open JavaScript-based links in new tab
- Uppity - jump to parent folder
- View Source Chart - view source code with logical groups highlighted
Thunderbird add-ons
- Leet Key - rot13, etc.
- Mnenhy - X-Faces and other custom headers
- QuoteCollapse
Web authoring
- Open Source Web Design (down as of 28 Sep 09)
- Open Web Design
- MyHedSpace (more open-source web design)
- HTML / XHTML validator
- CSS validator
