planestupid.com is doing something about it, and like similar efforts, they're making good use of visualizing the impact:
Polar Bear from Plane Stupid on Vimeo.
Others are working on this problem too. Virtual conferences and video chat are displacing carbon by cutting down on flights - although they have their drawbacks. And United Airlines Charity Miles program will let you donate miles to Conservation International (among other charities). Although, I wonder if the folks over at planestupid might come up with some sort of 'shame miles' subversive campaign. Blood-soaked red carpet premier boarding anyone?