Guardian Tread lightly is a new community site, which aims to encourage online communities into reducing their CO2 emissions through making weekly pledges and recording their actions against their pledges. The idea is that every pledge is simple, straightforward, and something that everyone can do, so that people who are normally put off doing environmental things because it sounds like a lot of effort will find Tread Lightly a good solution to easing their carbon conscience.
I've had a look and there's some interesting stuff on there. For example there's a chance to win an electric car, and if you complete 12 pledges you get a free eco shopping bag. Why not go and check it out, and maybe pledge to make some reductions in your CO2 footprint.