If you can't bicycle tour, perhaps the next best green way to travel is with Incredible Adventures of San Francisco- they run their buses on pure B-100 straight-up vegetable oil based biofuel. They claim it "emits up to 80 percent fewer carcinogens, greenhouse gases and particulates than petroleum fuel", and reduces America's dependence on foreign oil. And its not that clear-the-rainforest palm oil stuff that we complain about, it is from a San Francisco cooperative that promotes local production of biofuels from local recycled vegetable oil. We like the activities they offer as well- hiking, camping, low impact:"Incredible Adventures promotes Environmentally Sustainable Industry through the use of alternative fuels and minimum impact techniques." ::Incredible Adventures Thanks, Tipster Sarah