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.

CustomSoftware (http://customsoftwareconsult.com/extensions/febe/febe.html)

I use this extension and it's awesome!! The ONLY thing that I don't like is that you can't restore an entire profile without creating a second profile to be in to restore to the original. But a GREAT extension nonetheless.