Saul Griffith just gave the first presentation at Pop!Tech. He's an inventor, contributor to Make and Craft magazines, and a MacArthur "genius."Saul spent a few years meticulously tracking his own power footprint (he has technical reasons for keeping track of Watts rather than carbon). He factored in everything-home delivery of the NYT and electric toothbrush included.That experience informed his latest project, a personal impact calculator called Wattzon.com. There are lots of mediocre personal "footprint" calculators out there; on first blush Wattzon looks like a really good one.