Threadless is planting a tree for every t-shirt you buy this week. The donation goes to PlantABillion.org, who's mission is to plant a billion trees in the Atlantic Forest of Brazil. 

Threadless is a great site that sells t-shirts that are designed by people like you and me. The ongoing design contest has visitors voting on their favorite designs. The most popular designs actually get made into shirts, with the winner receiving $2,000. So buy a cool t-shirt from a cutting edge company and feel good that you are helping out our planet.