[update] For updated instructions on installing CheckGmail, see Updating CheckGmail to Fix Login Errors.
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. You can get started by just entering your username and password for Gmail and clicking OK. (If you aren’t comfortable saving your password to disk, leave the Save password option unselected. You will be prompted for your Gmail password whenever CheckGmail starts.)
Once you have CheckGmail running and know you want to keep it, set it up to start when you log in. Open System->Preferences->Sessions and click Add. In the Add Startup Program dialog, set the name value to CheckGmail and the command to checkgmail.
CheckGmail will display the Gmail icon in your notification area which will be grayed-out when you have no new messages. Hovering over this icon will display a preview of any new messages and let you take actions on them. When a new message is received, a small notification will slide onto the screen. Click on the icon to open Gmail in your default browser.