This webcast was a little depressing. Tom Sever discusses how he and others used the techniques of remote sensing to gain new insights into what caused the previously flourishing Mayan civilization to disappear. The answer includes deforestation and overpopulation. It doesn't paint a very rosy picture for people today.
One rather freaky bit: there's a picture, I think taken from a satellite, showing how (at the time the photo was taken, at least) the border between Mexico and Guatemala could be seen from space because of the pattern of deforestation.