My favorite Firefox Add-ons
This is about the Firefox Add-ons I use. This really is a complete list, I like to keep my browser lean. I'm fully aware that most people will miss things like Adblock, Pixel perfect and greasemonkey, but I don't use them.
Usability
Tab Kit: My favorite tab extension. Has many many features, I use it mostly because it allow more than one row of tabs and tab grouping/collapsing.
Clear Fields: This solves a quite annoying issue with Firefox and the xorg clipboard. Xorgs lets you paste things that you have highlighted with the mouse by simply clicking the middle mouse button. However, the previous contents of the search and address fields don't get cleared. This adds buttons to clear those fields before pasting.
Development and Webdesign
Firebug: The swiss army knife of web developer add-ons. To quote from it's description: "You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page". Very power- and useful.
Gridfox: Indispensable while making grid-based layouts or aligning text to a base grid.
Live HTTP headers: This is rather esoteric, but very useful for JavaScript debugging and web app development.
Web Developer: This is what I used before Firebug existed, and it's still useful today.
MeasureIt:This is very useful for quickly measuring the size of various elements on a page.
Privacy/Security
Cookie Monster: The best cookie manager I could find. I always block all 3rd party cookies, and by default no website is allowed to store cookies on my computer. Cookie monster makes it very easy to allow cookies for sites I visit. Another nice feature is to only allow session cookies for some sites.
Flashblock: Blocks all annoying flash animations. Can whitelist sites of course. A must.
NoScript: Blocks all (3rd party) JavaScript. Indispensable security tool and gets rid of most ads as well.
Nice list you've got there. Another add-on great at privacy and security is Billeo. It’s a free browser plug-in that manages passwords, saves receipts and auto fills forms. The tool is VeriSign secured and TRUSTe certified, so no security issues.
colorzilla is also a fave of mine, check it out: http://www.colorzilla.com/firefox/
I'm already using it :-D Time to update this list i guess