So just what is your "carbon footprint"? Try this great online calculator to find out if you're being green at home and at the office.

Do you know your car’s global footprint? The greenMeter, an iPhone application, allows you to compute your vehicle’s real-time fuel consumption. Among other things, this app shows the difference of about $300 in fuel costs between cruising at a speed of 60 mph vs. 70 mph for a medium sized car over 10,000 miles.