googsystray - System Tray Notifications for various Google Services

Googsystray is a system tray app for Google Voice, GMail, Google Calendar, Google Reader, and Google Wave. It lets you keep track of the information provided by those services without having to keep a bunch of Web pages open or constantly checking them. It notifies you of new events, such as messages or alerts, and provides basic services quickly.

Installation:
OpenSuSe user can install Googsystray using "1-click" installer - here

To install Googsystray in some other Linux distro, firstly make sure you have Python and pygtk installed, then download the .tar.gz archive and extract it. Open a terminal, navigate to the folder where you have extracted Googsystray, and run the following command:

sudo python ./setup.py install

Then, go to the bin subfolder from your googsystray folder, and double click the googsystray file.
To configure Googsystray, right click it's icon on your systray and select "Preferences":

To open an unread message, left click the service icon (Gmail, etc) in your systray (notification area).