environment { put your money where your carbon is
http://carbonfund.org/site/pages/calculator/
From what I've been able to find out, this non-profit buys carbon emission rights and retires them.
http://carbonfund.org/site/pages/faq/
According to their calculator, Nerdwife and I generate 36.79 tons of CO2/year for our home life (didn't calculate our respective jobs, but I just guess that mine alone will generate enough carbon to plunge the world into a second dark age).
I'm considering donating. Its a first step. I'm also looking into ways to reduce our consumption and decrease our carbon dependence.