AdBlock Plus
BBCodeXtra
BugMeNot
Clear Cache Button
CoLT (copies not just links but also their text, and does it in HTML, BBedit and Wikicode)
CookieSafe
Download Statusbar
DownloadHelper (lifts nearly any video from nearly any site and converts Flash videos to other formats)
Email This!
Flagfox (displays the flag of the country hosting the current web site)
Forecastfox
Google Gears
Greasemonkey
Novell Moonlight (open-source implementation of MS Silverlight, run on Linux, not sure about others)
Print/Print Preview (lets me use the Mozilla Suite's print/preview button)
RUWT? toolbar (
got scores?)
ScribeFire
Text Formatting Toolbar (gives me a button bar with formatting commands for places like this)
TinyURL Creator
US Department of Homeland Insecurity Idiocy Level