The best firefox extensions for web developers

Yet another reason to use Firefox

The CCSWeblog has a good list of must-haves for webheads using Firefox.

Web Developer - The absolute must-have extension for anyone who builds web sites, no matter how small or few and far between.
MeasureIt - No more eyeballing pixel widths!
ColorZilla - I shudder to think back on the huge PITA of getting hex codes for colors before this lovely extension… taking a screenshot, pasting it into Photoshop, using the eyedropper tool… how much time have I saved because of it? (Answer: lots.)
FireBug - As mentioned on The Javascript Weblog; just darn useful.
IE View - All the maddening bugs of IE without actually having to launch the browser. (With the caveat that it doesn’t do me much good on my Mac at work, where I don’t have IE/Mac installed.)
Live HTTP Headers - Go along for the ride from user interface to server and back, making all local stops.
EditCSS - Modify currently loaded stylesheets.
Cookie Crumbler - Convenient way to quickly clear cookies from a domain.
Clear Cache Button - Another small convenience that makes a big difference.