what do you use?

Firebug is the best thing. You can change things in HTML on the fly and see what it does. change css, javascript, html, traverse the DOM. it's great and I wished I had this years ago.

Foxmarks synchronize all your firefox bookmarks across different computers. I now have all my tabs, bookmarks, and links on both my lappies. that rules. I'm always losing links.

BugMeNot - Bypass registration on sites you'd rather not register for i.e. New York Times.

Remember The Milk (For Gmail) - Adds a to do list next to your e-mail.

Just discovered Foxmarks, and I second that.

god damn it... I keep editing my links tool bar and it will not save it no matter what I do. i thought it was getting it from foxmarks, but I can't find in fox marks where it would be getting it.

how the fuck do you delete your browsing history w/firefox? i can't find out how to do it for the life of me?

prefrences, privacy, clear private data

Fasterfox - Never used Firefox without it, so I wouldn't know whats it like without it

Forecast Fox - Pretty good weather program.

Do you need a lot of HTML knowledge to know how to use it properly?

Flashblock-- blocks flash on page and puts a button there so you can decide whether to view it or not.

Adblock--blocks ads duh

Reload Every--reloads the page every X seconds

Greasemonkey--lets you add javascript at the top of pages based on their url... its as easy to install the "userscripts" as it is to install plugins... for rttp i have lightbox user script so i can scroll through the images in the image thread one by one in a little black box instead of having a hard to load thread.

User Agent Switcher-- makes it so you can change the browser header you are supposedly browsing from. Some times I change it to funny stuff so people will get confused.