This widget for the Apple Dashboard announces the arrival of new mail. It is a direct extension to Apple Mail. But Apple Mail does not have to run all the time in the background. The usage is very simple and intuitive. Download it and try it yourself. MailWidget is available for Dashboard for four years now and is still being improved constantly with commitment.
Mia for Gmail (was Notifier Pro for Gmail) is a desktop Gmail client which sits politely in your menu bar.
