After using this for an afternoon I find that with a ten-second delay on the floater, I get the gist of each message as it comes in. I only really have to switch to Mail.app when I want to reply!

That's an exaggeration, of course, but I think this is an interesting interface tweak.

Neat. It's like Synergy or PTHiTunesNotifier (now YouControl), but for Mail. That plugin site that the mail.appetizer page links to is very cool as well! http://www.tikouka.net/mailapp/