Is this thing on?
ProfileManager is a standalone app that can be used to manage profiles for Firefox and other xulrunner apps. The profile manager which is built into Firefox is going away after 4.0, so this new app will be the best choice for managing profiles in future Firefox versions, but it works great with 4.0 and earlier versions as well, not to mention Thunderbird.
Some of its features:
You can download a build of the 1.0_beta1 version from ftp://ftp.mozilla.org/pub/utilities/profilemanager/1.0_beta1/. Myself and the others who have worked on this (principally Jeffrey Hammel and Mark Côté) would love feedback; feel free to leave comments or file a bugzilla bug if you find problems.
Note: by default, ProfileManager works with Firefox profiles. To use it with the profiles of a different xulrunner app, pass the name of the app to it as an argument, e.g., ‘profilemanager thunderbird’.