Enter FEBE (Firefox Environment Backup Extension) which automatically backs up your Firefox profile and all add-ons and extensions. The cool thing about this free extension is that you can now use your Box.net account to store your backups in the cloud.
Note: The free Box.net account has a file size limit of 10 MB which would prevent those of you (like me) with a large collection of extensions from uploading your FEBE backups. However, the premium Box.net account allows unlimited file size uploading so using it in that situation would be fine.
Pseudo Cloud Method
Another workaround would be to use your Dropbox account which doesn’t have a file size limit and the free basic account gives you 2 GB of storage. Once you select a dropbox folder to save your FEBE backups it will be available to you from any system you install the dropbox client on. While this isn’t exactly the same thing as saving straight to the cloud as with your Box.net account, it’s the next best thing and it’s free. The only difference is that you would need the dropbox client installed in order to sync all your files locally.
Needless to say, you can use any online storage service you use.
As for options, you can choose how often to create backups, whether to backup everything including your profile settings or just the extensions and other such things. Personally, I think you should choose these options to start with:
It makes a great deal of sense to backup everything you can on your computer, especially when it comes to your browser and all of its settings and add-ons. FEBE is an excellent tool that makes this process painless and automatic. Restoring your backups is just as easy. You can even pick and choose which backup to restore if you decide to save several sets of backups. In any case, it’s a real time saver being able to backup and restore everything we need for Firefox.