Today I was searching around the net for some tools that could help me on a really boring task... backup all my settings on Firefox and Thunderbird for a future migration (the official Firefox release 1.0 launch day is near and one of the lack on Mozilla product installations is that it's not so easy to maintain the settings during upgrades).
What's the result of this search? A great tool that works exactly as I want: MozBackup, an utility for creating backups of Mozilla, Mozilla Firefox, Mozilla Thunderbird and Netscape profiles. It allows you to backup mail, favorites, contacts, etc. and works really good. 
The main lack I've seen on my little test is that at the moment is impossible to backup all your Firefox and Thunderbird extensions, but all the settings are saved correctly. Unfortunately only a Windows version of the tool is available at the moment...
If you're a Firefox or Thunderbird user, this is a tool to have absolutely!