ive got a pretty huge list of extensions loaded:
googlebar - pretty much says it all
web developer - invaluable if you build webpages, highlights table cells, has links to html verifiers, speed reports, lets you see cookies set by a site and much more
JS Console Extras - adds functionality to the javascript console for lightweight debugging.
single window - forces most windows with target=_blank to open in new tabs.
ieview - lets you load a page into ie, useful for active x sites and ones that just wont play nice with ff. I may be deleting this since launchy duplicates the function
launchy - lets you select what program performs a function. i use it to view source of a page in my favorite text editor. it also can reload a page into ie, open mailto links, media links stuff like that.
status bar clock - i like auto hide toobars so i like to have a clock in the status bar
Diggler - makes it easier to move through directories and clears the location bar
BugMeNot - interfaces with
www.bugmenot.com to bypass compulsory web registration. works well with news sites and such.
downTHEMall - lets you download all links in a page, can be filtered for media type or other parameters
EditCSS - this is pretty sweet. you can open the css for a site, any site, in a sidebar and view the effects of realtime changes to the styles.
firefoxview - adds a context menu item to load pages viewed in ie into firefox. only fair i guess.
foxy tunes - control your media player from the status bar. scrolls the song playing and such. works with itunes, winamp, winmedia player, and xmms.
super DragAndGo - you can click a link, drag it, and it opens in a new tab. my favorite extension.
gmail notifier - keeps an eye on your gmail account and lets you know when you have mail. also lets you open gmail with a single click.
Linkification - turns plain text urls into links
javascript debugger - if you work with javascript this will save you tons of time.
disable targets for downloads - prevents download links from opening a blank window.
user agent switcher - lets you spoof your user agent, makes sites think that your firefox browser is ie. this way you can see if a site that claims it doesnt work with ff does or not.
a4seo - mostly just lets you look at backlinks to a page. if you are involved with search engine optimization or rankings at all this is kind of helpful.
adblock - filters ads from web pages
gcache - lets you see the google cache of a page.
man i guess i really do have alot of these.