One Ton sells some pretty snazzy t-shirts, and for each one they sell, they purchase one-ton of CO2 offsets from the Chicago Climate Exchange.

The site also has some great recommendations (easy too!) for reducing your carbon emissions:

Eat meat-free meals every other day.

Vegetarian food requires much less energy to produce.

CO 2 savings = 487 pounds

Vegetarian food requires much less energy to produce. CO savings = 487 pounds Park the car for 60 days this year.

Walk, cycle, or take public transit.

CO 2 savings = 917 pounds

Walk, cycle, or take public transit. CO savings = 917 pounds Switch from hot to warm or cold water for every load of laundry.

CO 2 savings = 600 pounds

Read more @ One Ton

Via Treehugger