Carbon offsets are becoming an increasingly popular way for famous people to avoid having "Environmentalist is Really Private Plane Flying Hypocrite" stories written about them. Average Joes who love their SUVs but fret about global warming buy credits with companies that do things to reduce net greenhouse gas emissions, like plant trees.
At Wired, Lore Sjöberg proposes other applications for the offset concept. My favorite:
Jerk Offsets: You know what's stressful? Being nice. Studies show that every time you choose not to yell at a waitress for bringing you water with ice when you asked for water without ice, it takes six months off your lifespan. If only there was some way to berate and abuse everyone around you and still be considered a nice guy ... well, you see where we're going with this.
Fork over the bills and we'll go out and perform random acts of market-driven kindness. Then the next time a pedestrian tries to cross the street right in front of your Beemer, you can yell at them, make up new sex acts for them to try out on pets and family members, throw your half-empty Starbucks cup right at their head, and then explain that you've fully offset your antisocial acts and, in the big picture, you've basically just bought them an ice cream cone and knitted them a hat.
They'll thank you, unless they've bought jerk offsets as well, in which case they don't need to thank you.
Read more about markets in carbon and other offsets here.