FoxTester: Easy Way To Try Or Install Any Firefox Version In Ubuntu (Including Firefox 4)

Want a way to try out the latest Firefox 4 (currently beta 5 - released today) without making any changes to your system? You should try FoxTester, a Firefox extension which you can use with the Firefox version from the official Ubuntu repositories (or any other version), that you can use to install and launch multiple Firefox versions without affecting your default Firefox user profile.