Gmail recently introduced multiple account sign in which lets you switch between different google accounts making it easier for you to check emails quickly. So now how do you get notified when you get mails in your multiple account, Get Spiffy.
This windows based application supports multiple accounts which means when you get a new email in any of the account you will get to know it.
You are notified in which account you had received the new email and notification to the account can be configured separately. As of now 5 accounts are supported which includes Google Apps accounts also.Download from here