If you use Mozilla and also have a GMail account, then this small utility notifies you in your browser when you have new GMail
The program is called Gmail Notifier 0.3.1
Enjoy
Version 0.3.3 is already out. I’m using it in Firefox almost as long as i have Gmail account. Great stuff 
Otherwise Google has released a stand alone official notifier too
There is also another notifyer which sits in the tray called GTray.