Notify provides a simple and elegant way of keeping track of what's in your Gmail inbox.
Notify is a Gmail notifier which completely rethinks what a Gmail notifier should be. Includes support for multiple Gmail accounts, awesome tabbed account organization, and configurable notifications on a per account basis.
2.0 is re-engineered from the ground up to be easier to use, prettier, and most importantly to be more useful to the user. Support for Google Apps, MobileMe, Rackspace Email, and more has been added.
With the Pro version ($10) you can read full HTML-emails, as well as mark them read, delete them right there on your desktop and send a message from any of your accounts without ever leaving Notify.