CO2 offsets fund projects that have a net-positive effect on the environment, thereby nullifying the negative effect of the pollution you create.
TerraPass - supports wind and biomass projects.
Carbonfund - non-profit offsetter that supports solar and wind farms, promotes cleaner industry, and plants trees around the world.
Native Energy - supports Native American alternative-energy projects.
Consumers' Guide to Retail Carbon Offsets - not all offsets are created equal.
Climate Counts - compare the carbon-cutting commitments of several major corporations.
Post borrowed from Ideal Bite.