We've created a Facebook application to help you and your friends be a little bit greener.

This application allows you to issue challenges to your friends and to yourself, such as fitting low-energy light bulbs or turning down the thermostat at home.

The application will then keep track of how much CO2 you and your friends are saving, as well as telling you the equivalent amount of trees you've planted.

It will also give you an idea of what you and all your friends could accomplish if you just made one small change. It really is amazing to see how much you can achieve by working together!

*Facebook is a registered trademark of Facebook, Inc.