GPeek

Using the new GMail atom feed, GPeek is able to display all the pertinent information relating to every piece of new mail in your inbox: Subject, sender, time and the first few lines of the email. This all comes in a stylish, intuitive package that becomes as small as is practical and expands dynamically as is needed. GPeek also supports multiple instances so you can check multiple accounts and provides quick access to your GMail inbox by automatically opening your browser and logging you in. The common sense preferences allow you to customize GPeek so that it behaves best to suit your mail-checking needs.

Requirements:

Mac OS X