what follows is a list of the top 10 Firefox extensions I use, in no particular order.
Xmarks Sync is clutch for anyone with more than one computer that hates having disjointed bookmarks. Xmarks allows you to sync your bookmarks between multiple machines, saving a ton of hassle. It was in peril of being shut down, but luckily it was recently bought and will continue as a freebie.
Form History Control
Form History Control allows you to see all of the saved form entries in your browser. It is useful for managing/deleting saved form information which you may not realized Firefox had saved, but which could be detrimental if it fell into the wrong hands (such as credit card numbers, etc).
DownThemAll! is simply a download manager done well. I sometimes have issues downloading from sites like rapidfire, however, that tends to be on the site end, not on this software. Useful if you download big files that need to be paused and continued.
HTTPS Everywhere is one of my favorite extensions because it treats a growing internet problem: stolen credentials. Many sites have a secure https option, but do not default to it, such as Twitter (and, just recently, Facebook). This extension will check to see if the site you’re visiting has https (or SSL), and if so, redirect you. No more stolen login information when you login from Starbucks.
StumbleUpon simply assists in finding interesting new websites when you’re bored. A simple interface and sure to send you somewhere cool after a few clicks.
ReminderFox is a to-do/checklist manager. Nothing fancy, but it gets the job done!
Screengrab allows you to take screenshots from your browser in a number of different formats. Most machines have fullscreen capture built-in, but Screengrab allows selections, which is a timesaver.
YSlow is another developer tool that tells you why your site is loading slow. Of course, my site loads slow, but that’s just because I’m too cheap for a new server ;)
Extended Copy Menu
Extended Copy Menu is probably the simplest of these extensions, but also one that I use most often (now that Copy Plain Text has died). In trying to be efficient, I am constantly copy/pasting text between web pages. I usually end up having to paste into a plaintext area (like the URL bar) and then re-copy/paste so that I don’t get the text formatting along with it. Now? Problem solved :)
What are your favorite extensions? Let me know in the comments!