Google has released the Gmail Notifier: a little software gizmo that runs on your PC (Windows 2000 or XP only).
You install it, tell it your gmail username and password, and then it runs in the background popping up a little email summary in your screen whenever a new message arrives in your Gmail account.
You can get the Gmail Notifier at http://toolbar.google.com/gmail-helper/
(p.s. congrats to Craig S who won our gmail giveaway competition. Check back on September 1st for another giveaway of 4 gmail accounts.)