UbiGreen, a cell phone application that's been developed jointly by the University of Washington and Intel, will keep track of how you travel and let you know how green you're being.
It uses built-in accelerometers like the iPhone has to figure out if you're walking, running or biking, and cell phone towers to determine when you're in a vehicle. If you're obviously traveling in a vehicle, a quick questionnaire pops up and asks you if it's a car, train, or something else.
To offer a little incentive, on the screen of your phone you'll see a tree. The greener you travel, the leafier your tree will be. Eventually, the team hopes that the tree will gain or lose leaves entirely based on information from an accelerometer — so no lying that you're in a car if you're flying.
UbiGreen was inspired by UbiFit, another app by the same team. UbiFit keeps track of your exercise and, similarly, grows a bigger garden of flowers the healthier you're being. Sadly, it doesn't appear like either of these two apps will be released for another year or two.