Basically, it asks you a few questions about the way you live, and figures out what your "ecological footprint" is. Mine is 4.1, the average American's is 9.7 (yikes!). As they say, "Worldwide, there exist 1.8 biologically productive global hectares per person." Sucks for us, I guess, huh?
Food - 2 (I eat well.)
Mobility - 0.2 (I use public transportation or walk almost exclusively.)
Shelter - 0.9 (Modern apartment building w/ modern wiring.)
Goods/Services - 1 (Stuff.)