Since my old Firefox post is woefully out of date, here’s a list of the extensions I’m currently running and what they do (well, the “what they do” part may be expanded upon later).
Adblock Plus
BBCodeXtra
Better Flickr
Better Gmail 2
Better GReader
Faviconize Tab
gDocsBar
Google Browser Sync
Google Reader Notifier
Greasemonkey
meebo
RetailMeNot
Slashdotter
Image Zoom
Secure Login
Autofill Forms
Video Downloader
Long Titles
Linkification
CustomizeGoogle
