#19 Gmail Manager
What it is: Allows you to manage multiple Gmail accounts and receive new mail notifications. Displays your account details including unread messages, saved drafts, spam messages, labels with new mail, space used, and new mail snippets.
Why you should use it: A no-brainer if you are a Gmailer, but there are early complaints that the extension often forgets account passwords and if you use multiple Gmail accounts you are out of luck.
Where to get it: Click here.