A little program that sits in your system tray, (as shown below), and alerts you when you receive emails and event responses. Swingfree also let you know when other things happen so that you can stay informed on the site, relative to your activity, without needing to stay logged in or keep a browser window open.
Mia for Gmail (was Notifier Pro for Gmail) is a desktop Gmail client which sits politely in your menu bar.
