Always have a browser tab open to your Gmail account? CheckGmail is an application that can monitor your Gmail account for you. It’s unobtrusive, feature-rich, and easy to configure.

Install CheckGmail from the package checkgmail (click the link to install), or by running the command below in your terminal:
sudo apt-get install checkgmail

Start it for the first time from Applications->Internet->CheckGmail. You may have to wait a few seconds for the configuration window to appear.