Over a period of time I have added tons of bookmarks to Firefox, losing them would definitely be disastrous. However there are ways in which users can backup Firefox bookmarks, make bookmarks portable to multiple browsers and synchronize them between browsers, but these solutions are not automatic.
However we just came across a useful Firefox add-on that will allow users to easily backup their Firefox bookmarks, saved passwords, browsing history, cookies, search engines and other profile settings automatically on a day to day basis.
The Bookmark Backup extension for Firefox is a pretty handy extension that will allow you to create regular backups of your Firefox bookmarks, passwords and other settings automatically once a day.
You can choose where your bookmarks should be stored and which other custom settings you want to backup everyday. The backups can come in pretty handy when you install Firefox again or have some problems with your profile.