GMail Atom Feed

You've probably known about the gmail atom feed
http://gmail.google.com/gmail/feed/atom

But did you know you can pull just on label?
http://gmail.google.com/gmail/feed/atom/SomeLabel

And you can also pull your All Mail. So if you get a new message and you have a filter that puts it into a label and archives it then you can pull your all mail to get every unread message in your account.
http://gmail.google.com/gmail/feed/atom/all

Only reason I could see for using it is to write your own notifier. But thought it was cool.