Gmail Notifier Pro is a program that can check your Gmail accounts and warn you if you have new emails on them.
You can enter the details (email address and password) of your Gmail account, and the program will check periodically if you have new messages. If you do, it will pop-up a notifier that will have an "Open" button that will let you open and read your new emails online. The "Menu" entry on the interface will let you visit the program website, look for updates and access the program´s help. The "Check Now" entry will scan your Gmail accounts for new messages. "Manage Accounts" will let you modify the settings for each account, as well as the theme you want to apply for them, details about the notifications, the connection you will use to check them and more. The same menu will open when you press the "Options" menu entry.
The free version supports all features of the registered edition and can be used for an unlimited period of time, but it is limited to monitor a maximum of 2 Gmail accounts.