Since I'm one of the few guys that doesn't live in CO, I have to drive up from NM for the USGP weekend in a couple weeks. Nothing I can really do about it, so I went and bought some Cool Tags (10 of them) to try and offset the emissions from my car.
Blatant plug here: It could not have been easier to buy the Cool Tags. I started at the Clif website, clicked the Start Global Cooling logo, probably took less than a minute. Also was able to sign up for email updates on how the wind farms are progressing.
You don't have to just buy Cool Tags, there are a number of options at the Native Energy site. I think I'm going to offset my wife's driving CO2 emissions for her birthday as well, using this. Don't worry, I got her other stuff too...