Having recently moved to Firefox from Chrome (since Google messed with the multi personality settings) I was overjoyed when I saw this plugin.

It seems to do exactly what it says on the tin .. the only downside I can find so far is that it doesn't seem to sync between machines, so all the preferences need to be manually copied from laptop to desktop / etc .. which is a bummer.

Would be 5 stars if only the profiles sync'd along with everything else through Firefox Sync