I am using WebDeveloper - HTML validator - Measurelt - Modify Headers -ASCII to unicode - UserAgentSwitcher - SEOLinks - LiveHTTPHeaders - ContextHighlight - Google ToolBar - Quick Locale Switcher Mozilla release Firefox 1.5 this week
Web Developer, SearchStatus, All-in-One Gestures, Tab Mix Plus, ColorZilla, IE Tab, and my very own POTO Sidebar!
Adsense notifier, Google page rank status, SEOpen, Search Status, InFormEnter, BBcodeXtra, Confuscator and Nofollow highlight but i had more.
adblock, foxytunes, gtranslate, tabbrowser preferences, wellrounded, forecastfox, define word, leet key, customize google and disable targets for downloads
Google Toolbar Stumble Toolbar Gmail notifier Web Developer LoremIpsum Generator GreaseMonkey and most importantly... SessionSaver - so when the bloody thing crashes I don't lose anything.