Please.. only links to the main extension site.. Most here are very cautious with software from sites we know nothing about.
And please.. descriptions.. I don't want this thread to degenerate into an extension naming contest..
meanSpleans links:
Flashgot
BugMeNot can't be found on the main FF extension site.
PDF Download
McAfee SiteAdvisor can't be found on the main FF extension site.
ChatZilla
trache's suggestions:
User Agent Switcher
Adds a button that lets you change the user agent of your browser (IE, Netscape etc.)
All-In-One Gestures
Mouse gestures in Firefox
Adblock
Let's you block elements and ads on pages with the source of the ad/element via wildcards.
Flat Bookmark Editing
No more going into properties of a bookmark to edit it.
Bookmarks Syncronizer
Lets you connect to a FTP or WebDAV server to syncronize your bookmarks.
Firefox Extension Backup Extension
Backup your extensions and several other things in your profile like bookmarks, settings etc.
FoxyProxy
Easy access to your proxy settings and adds several usefull button functions as switch proxy etc.
Sourceforge Direct Download
Automatically download things from Sourceforge from your favourite mirror.
Video Downloader
Download streamed videos from sites like YouTube etc.
Ook? Video Ook!
Let's you download embeded videos from several types of systems.
MontanaXVIs suggestions:
SiteAdvisor could not be found on the main FF extension site.
IE Tab
Embeds an IE session in a tab, usefull for sites that won't show right unless you have IE as you browser.
DownThemAll!
Download mannager/accelerator. Quickly download all the images from a page with just a few clicks etc.