Gmail Manager
I have three gmail accounts and use each of them for their own purpose, private use, Japanese mailing list and major mailing list. In the browser, I have to logout once and login another again every time to change accounts. It was really a pain to do each time. "Gmail Manger" has solved this problem. It is one of firefox extension. Now I can open all of my accounts at the same time and also it automatically checks all of them with a notifier. It is quite convenient and makes my life a little bit easier.
