Most calculators that tally your environmental impact on the planet are just that--calculators. This one adds a little bit of graphical representation to give you a better idea of how much you're consuming. It also lets you compare yourself to others who took the test. Most sustainable lifestyle: Green Party respondents. Least: Libertarians (Thanks Ron Paul!)
Apparently, if everyone lived the way I do, we'd need another three planets. And I don't even drive a car.