[martin_fierro]

What extensions are you using?

Mine:

Adblock Plus 0.7.1
BugMeNot 1.3
Colorful Tabs 1.4
Ext 2 ABC 0.4
Fasterfox 1.0.3
Foxmarks Synchronizer 0.72
J2SE Runtime Environment 5.0 Update 6
MediaPlayer Connectivity 0.6.3
Searchbar Autosizer 1.1
SearchPluginHacks 0.1.3
Talkback 1.5.0.4
User Agent Swithcher 0.6.8
WebMailCompose 0.6.6
WindowResizer 0.5

[Clara Lou]

I have quite a number, but they work smoothly and so does FF itself:
Clear fields [clears address bar, google bar]
Colorful Tabs [different color for each tab]
Dictionary Tooltip [this is EXCELLENT]
FireFTP [very handy]
FirePhish
Flashblock
Forecastfox
Highlighter
no-referrer
NoScript
PDF Download
QuickNote
RestartFirefox
SearchBar Autosizer
Tab Clicking Options
Tabbrowser preferences

[bwteim]

I'm a piker. Not nearly as many. Using Firefox 1.5.0.4 with

Adblock Plus 0.7.1
Dom Inspector 1.8.0.4
Talkback 1.5.0.4
NoScript 1.1.4.1
Tab Mix Plus 0.3.0.5
Extended Cookie Manager 0.7
Advanced Dork 2.0 Beta 5
Wayback 0.2.3

Have Privoxy on top

[zeugma]

I'm suprised none of you mentioned Xinha Here!

It makes posting well-formatted posts on FR a breeze.