Carbon footprint

Two sites claim to help you estimate your "carbon footprint":

• http://www.carboncounter.org/offset-your-emissions/personal-calculator.aspx
• http://www.epa.gov/climatechange/emissions/ind_calculator.html

The first, I think, is worthless -- basically a gimmick to raise funds for something called "The Carbon Trust." The second looks like it might be a little better, but I haven't checked it out yet.