Greenwave is a Facebook application that encourages and facilitates cooperative participation in environmentally friendly team challenges. Greenwave users invite their friends to join them in a commitment to simple actions that make a positive improvement on the environment. Visualizations that illustrate the collective impact of users' cooperative action will demonstrate that small steps are making a positive impact on the environment. Challenges range from taking your reusable mug along with you to the coffee shops, to boycotting plastic and paper bags in favor of cloth ones, to giving up the car for your commute to work. It is our hope that by participating in our challenges, users will have fun changing their lifestyle for the environmental good and inspire others to ride the green wave.