Auto Copy – Copies selected text to the clipboard automatically. Like Linux or mIrc.
AutoPager– AutoPager is a firefox/mozilla extension that autoloads the next page in background.
Better GCal – Enhances Google Calendar with a compilation of user scripts and styles. All scripts copyright their original authors. Click on the script homepage in the Help tab for more information.
Better Gmail 2 – Enhances Gmail with a compilation of useful features written by Greasemonkey user script developers. All scripts copyright their original authors. Click on the script homepage in the Help tab for more information.
Better YouTube – A compilation of useful Greasemonkey user scripts for YouTube. All scripts copyright their original authors. Click on the script homepage in the Help tab for more information.
ColorZilla – Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies
Cooliris – Cooliris (formerly PicLens) transforms your browser into a full-screen 3D Wall for searching, viewing and sharing the Web.
Flashblock – The plugin blocks flash from running. It acts on all sites by default, but lets you set ‘whitelists’ of sites that can use flash, such as youtube. For blocked sites (those not on the whitelise) you get a window of the right size on the screen, and a ‘play’ button you can click if you want to load the animation. Here is an opera version.
Fasterfox – A bunch of tweaks to speed up firefox simply without manually tuning the registry parameters. Can be set to exceed the RFC specs if you want. Also provides a page load timer in the bottom right which is I like. See how much of a change you get after installing flashblock
Autocomplete Manager – When you type into the default firefox location bar, you get ‘autocomplete’ suggestions based on the part of the URL you typed. This plugin enhances that so it automatically searches on bookmarks, and even web page titles from your history. If you keep a long enough history, it could almost render your bookmarks obsolete.
Firebug – Essential for anyone who does web development. Install it, then for a page you want to analyze click Tools/Firebug. Click ‘inspect’ and point your mouse at any part of a web page and it’ll show a breakdown of the HTML in that section only, and let you modify the source ‘live’ to test fixes. Great for showing how web pages are composed, and it’s a much nicer alternative to a full ‘view page source’ option. Firebug and the inspect facility can be added as icons to your toolbar, so it doesn’t clutter up your browser out of the box. There is also a YSlow plugin that you can add after installing firebug to perform performance analysis on web pages.
FoxEar – Essential internal tool that gives you a sidebar to interface into DogEar.
Fast Video Download – It downloads videos from YouTube. You get an icon in the bottom right that you click when you’re on a page with embedded video, and it lets you save it.
Remove It Permanently – (RIP) RIP lets you right click on any section of a web page (Such as a sidebar or advert) and specify that it’s removed from all futuring rendering of the page. By using this carefully you can reclaim a lot of your browser screen area.