Environmentalists who drive SUVs and other gas-guzzling vehicles can now pay for a sticker that will soothe their conscience. TerraPass, brainchild of a University of Pennsylvania Wharton School class project, sells a sticker to confirm the buyer's environmental credentials. Pricing is based on the amount of estimated carbon dioxide emissions produced by the vehicles. SUV drivers pay $79.95, while hybrid stickers go for as little as $29.95.

Carbon dioxide, the same gas humans and other animals produce by exhaling, is considered by some a "greenhouse gas" harmful to the environment. TerraPass uses the money from proceeds to fund environmentally friendly energy projects such as "wind farms" that produce no carbon dioxide. TerraPass is managed by MBA students who have no salary but take an undisclosed "equity share" in the company.

Assuaging guilt and fueling a sense of environmental righteousness are the usual motivators. Rusty Feasel, a TerraPass customer in Dallas, makes his living selling all-terrain vehicles. "I'm looking at this TerraPass to buy off my guilt about what I'm selling now," Feasel said.