Another extension that is part of my frequently used Firefox extensions collection.
Firefox Extension Backup Extension (FEBE)
FEBE 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.
FEBE backs up your extensions, themes, and (optionally) your bookmarks, preferences, cookies. and much more
There is realy not more to say about this extension. I find it very usefull to have the same tools that I use at work, also at home.