I used this website to calculate the amount of CO2 pollution I contribute by taking a trans-pacific airline flight. Next I clicked a button that allowed me to "offset" this pollution by donating to projects that cut back other sources and/or help to absorb such pollution. Interesting idea -- to assuage one's guilt and do something effective to reduce the problem.
You might play with this site to calculate how much pollution you contribute at home, driving a car, etc. It's interesting to find out how much money they believe you owe to compensate for your pollution.http://www.climatecare.org/Individuals/index.cfm