I'm dual booting Windows 7 and Ubuntu 9.10 Karmic Koala and want to bring over my Firefox profile, I know where it is in Windows, where is it in Ubuntu? I feel like I've looked everywhere.
/home/yourusername/.mozilla/firefox/bunchoffunkycodes.default has some things like where you'd have your userstylesheet override and your bookmark backups in JSON format. remember you won't see hidden ".files" unless you have "show hidden files" in your edit>preferences (if you're using the GUI to navigate) or the -a option if your using "ls" in the command line.
/etc/firefox(versionnumber)/profile/ should have your bookmarks in HTML format, prefs.js, and a folder called "chrome" where your user stylesheet overrides are (but if you have a user stylesheet you should place it in the first path I mentioned, in your home directory).
There's also /usr/lib/firefox(versionnumber)/defaults which should have a simlink to the profile folder mentioned above, and some other stuff.