http://www.dgp.toronto.edu/~shbae/ilovesketch.htm

this looks like something that can change the way we model forever, I have been thinking for a long time how to make something like that possible. I think this people are on the right pass, if only the can figure out how to allow user to control it in all 3Ds at the same time, I guess this is what we need 3D holograms for.