FEBE (Firefox Environment Backup Extension) allows you to quickly and easily backup your Firefox extensions. In fact, it goes beyond just backing up -- It will actually rebuild your extensions individually into installable .xpi files. Now you can easily synchronize your office and home browsers.
Have you ever been interested in what extensions are available for Firebug? If yes, take a look at what I have found. Frankly, I was quite surprised how many Firebug extensions already exists out there.
Linkwad lets you save and restore tabbed browsing sessions called wads. Wads can be shared and accessed from any computer. You can also share your "wads".
Achtung: Mit FF 1.5X funktioniert nur die 0.7x Version!! The Wikipedia extension makes editing of Wikipedia pages easier by adding a new toolbar to your browser and by providing new menu items in the context menu (right mouse key).