He's a living legend, one of history's greatest and most innovative western worlders, and noboy knows who the hell he is. Honestly, I think people should give the guy some credit. He's the original John Lennon, man, the original hippy. Google it.
He wrote, "Walden", a really great book on enviornmentalism and self sufficiency. He was friends with Emerson and was part of a movement of some sort at the time.
I think Thoreau's greatest contribution to all of us, is his ennoblement of the idea of nonviolent resistance and to THINK for ourselves.