The Carbon Fund clearly promotes reducing your impact on the earth as much as you can (by carpooling, recycling, biking to work when possible, and other means), and then offsetting what you can't. For me, that would be my trip out to Washington to begin my stint with AmeriCorps, two trips back home after a family member was diagnosed with cancer, and the offsets required to heat the house that I share.
All told, it would cost me about $79 to offset a year's carbon production. This seems like an easy, efficient way to offset the carbon that I use.
How do you reduce your carbon footprint?