I've just watched a "documentary" on the ABC about these crop circles. All the interviewees talked about forces in the Earth, lines of energy, vortexes, plasma 4th dimentional energy constructs intersecting the 3 dimentional world... These people have a lot of money tied up in this gravy train.
Circlemakers.org says it's some blokes with a lot of planning and some boards.
Hmmm... Who to believe? What would Occam say?