[BDBohnzie]

Let's see...besides the ones you've already listed...

ColorZilla - Web Design tool, allows you to pull colors from elements on the page you are browsing

Domain Details - Allows you to see the server type, IP address, etc of whatever website you are browsing

Extended Copy Menu - allows you to copy in plain text as well as normal copy, big plus when trying to copy text without pulling the formatting along with it

Firebug - awesome web development tool

FireFTP - ftp client inside Firefox, I mainly use it to upload crap to my Comcast account

FireShot - great screen grab tool

FoxLingo - allows you to instantly translate into many languages, using different many different translaters

Glazoom - allows you to zoom in and out easily

Hide Menubar - hides the menu bar for more visibility (use Alt to bring it back up)

IE Tab - great tool that allows you to view the current page in IE without having to open IE. I use it a lot when doing cross-brower web developing.

Last.fm - Scrobbles any music to Last.fm from Slacker, Pandora and Napster

MeasureIt - another great webdev tool, ruler that gives you a pixel height and width measurement for any element on the page you are viewing.

meebo - Instant messaging in Firefox, allows you to log into all the major IM networks

oldbar - Firefox 2 style Url bar

Web Developer - another great webdev tool