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 and restores your extensions, themes, and (optionally) your bookmarks, preferences, cookies. and much more.

Backup as little or as much of your Firefox environment as you wish.  Perform backups on demand or schedule daily, weekly, or monthly unattended runs.  Sequential backups can be stored in timestamped directories so you can restore back as far as you like.

You may specify “User-defined” items to have FEBE backup Thunderbird, Greasemonkey scripts, or virtually any data on your computer – Firefox related or not.

Version 6.0 allows for automatic or manual uploads to your Box.net account.  Online restores are also integrated into FEBE.

For more information see this Link