Marketplace, the money and finance news program from American Public Media has a "game" on their site which asks some simple questions about the way you live your life, and then gives you an assessment of how many earths we would need if everybody lived like you do.

They try to keep it light, and it isn't exactly new information that Americans gobble up a resource chunk ten times bigger than they deserve. Still it's eye-opening to look at state averages for energy costs and realize what my family of four, living in our new suburban dwelling, consumes in a month. Air travel -- even if it's work related -- is another big multiplier, as there may not be a more resource-intensive activity engaged in by ordinary Americans, save the few who still race ocean-liners into the sides of oil tankers for sport.

If you click through the survey and your final results, the game's fun really begins. You can compare results to those of people in different states, income brackets, genders and birth years. You can even stack yourself against some radio hosts.

I ended up needing about 4 earths to sustain my lifestyle, and I ride my bike to work. Visit Consumer Consequences and find out how many earths you'll be needing. (The background information on their Frequently Asked Questions page is quite useful as well.)