Gmail on Rocket is a Mac OSX Gmail nofiticator. The author arrived to the conclusion that it would be impossible to make a good notifier using their promoted ATOM and XMPP protocols because of moronic implementation. While they work with "conversations" instead of emails there's no way to know how many unread emails are in the inbox.
Mia for Gmail (was Notifier Pro for Gmail) is a desktop Gmail client which sits politely in your menu bar.
