Firefox Extensions, 2009 Edition Top 10
AutoCopy:
It copies any text you select on the web, no Ctrl + C necessary. For pasting into text forms, simply hit the middle 
mouse button rather than Ctrl + V. It also fixes really long, wrap-broken URLS automatically.
Google Gears:
Gear’s is an easy-to-install add-on. Primarily, it takes Google apps offline – Gmail, Google Reader, Docs and Calendar but a handful of other apps make good use of its mini-database powers, including Remember the Milk and PassPack.
Personal Menu:
Personal Menu is the next-generation version of the Tiny Menu, achieving the same basics: Giving the web content you’re looking at more space to breath. It does this by stripping the screen-wide menu bar at the top of Firefox’s windows and converting it into a single drop-down menu and lets you choose which of those menus shown up in it. Keyboard shortcut ninjas can enable an option to temporarily bring back the menu bar when Alt is pressed, and the extension auto-adds a history and bookmarks button to the main toolbar to compensate for the two most active menus.
Better Gmail 2:
Better Gmail 2 fixes or answers a lot of our Gmail complaints and wishes in one neat package. You can individually enable or kill any of Better Gmail’s more than a dozen fixes and improvements.
DownThemAll:
DownThemAll is a selective, powerful download manager. It makes short work of snatching all the images on a page (including those links to the “bigger” or “zoom” versions), all the MP3s off a music blog, or any other kind of filter you can set up.
Tab Mix Plus:
It controls which links open in a new tab, new window, or same window to an OCD-friendly level, adds key features like italicizing the text on tabs you haven’t viewed yet, and super-powers Firefox’s undo closed tab feature.
Automatic Save Folder:
Automatic Save Folder places the files you download in a certain folder on your system based on the file extension or the site you get it from.
Adblock Plus:
Any advertisement that you find distracting on the internet can be right-clicked on and killed in perpetuity with “Adblock Image”.
Greasemonkey:
Greasemonkey is a meta-extension of sorts. It does nothing by default when first installed; the power lies in Greasemonkey user scripts developed by JavaScript. If you don’t like seeing labels on your Gmail messages, but wouldn’t mind seeing them when your pointer hovers over them, there’s a fix. You can find Greasemonkey scripts all over the web, but if you’re just getting started, you may also want to check out Userscripts.org, sort of like Mozilla’s add-ons site but for Greasemonkey scripts.
Foxmarks/Xmarks:
It’s nearly faultless at keeping your bookmarks and passwords synchronized between browsers on any platform, and stores them on a site you can visit from any browser where you can’t install an extension.
