To those who commented, thanks for posting such useful resources on the subject.

I also think that when companies choose to pay offsets, they are rehearsing for the future. They are getting ready for a taxation that will eventually come for carbon usage. Those companies that thoughtfully offset today will glide into the taxed-capped future, while those that don’t will face an unforseen spike in operational costs. I compare this to 2001-2002, when companies voluntarily expensed stock option purchases even before it was required. They coasted through the changes, while others suffered from the shock of regulation.

For individuals looking for offsets they can trust, here’s a list of companies that met Environmental Defense’s criteria. (And no, we don’t get any money from these companies.) http://fightglobalwarming.com/page.cfm?tagID=270

Mike Corrales is right: “It is important to note that this is NOT a green solution because we are buying Renewable Energy Credits or carbon offsets…We are not paying a penance for our emissions sins, we are just not committing the sins in the first place.”