At the Web 2.0 Summit, Saul Griffith of Makani Power pointed out that a person's carbon footprint is just part of the issue when it comes to living a green life. It comes down to energy consumed, he says. Thus WattzOn, a site that helps you visualize your total load on the planet (actually, technically speaking, the sun).
The service lets you enter in your energy-consuming behaviors, from transit to food to goods purchased. It calculates not just energy taken up by a device (like a washing machine) but the energy it takes to build it, amortized over its projected life.
Entering accurate data can be difficult unless you are sitting down with your power bill and grocery receipts nearby. It would be much better if the service could tap into your financial or utility providers to get data. But the site does give you a good idea of your energy use, and it shows you two valuable things to help you understand your impact. First you can play what-if games, and see what happens, for example, if you take transit more or change your diet to vegan.
Second, cute graphics show you how much energy you're using compared to other people on the site and around the world, and also how many barrels of oil, wingspan wind turbines, or acreage solar panels it would take to fuel your life.
See the site and get depressed. Then maybe change your footprint.