A student group from the virtual reality lab at the University of Tsukuba in Japan has developed shoes that allow the wearer to walk through virtual worlds. Right, Hiroshi Tomioka, one of the developers of the powered shoes goes for a virtual walk.
Here's a closeup of the sole of the shoe. Three sets of motorized rollers drive the skate backwards in time with the pace of the walker to cancel his forward motion and remain in place--similar to a treadmill. Direction is changed by rotating the computer and monitor around a circular track on the floor.
The virtual walker must use the monitor to see where he's going.