I have lots
Adblock Plus - Block ads
Add N Edit Cookies
British English Dictionary
Chatzilla - IRC client
Copy Plain Text - Copies text without formatting
CustomizeGoogle
Download Statusbar - Shows downloads on status bar instead of a new box.
DownThemAll! - Download anything on the page, at once.
Fasterfox - Make it faster
Google Toolbar for Firefox
IE Tab - Use Internet Explorer in Firefox
ImageShack Toolbar
Menu Editor - Edit the menu's
StumbleUpon
Tab Effect - Makes a cool effect every time you change tab, requires DirectX 8.
Tab Mix Plus
Talkback - Send crash information
Text Links - Double click text links
UI Tweaker
Web Developer
WindowsUpdate - Puts a link on menu
Download various embedded videos:
Download Embedded
VideoDownloader
GetVideo