I believe that the best of the AR systems coming up (because, let's be honest, this is a kind of AR), is CastAR. It gives the wearer the ability to see any CG object above/inside a given physical surface. It works using projectors mounted on glasses and a retro reflective surface (I.e., always reflects light the direction it came) to produce an image that only the wearer sees, at a distance, without straining eye focus. The possibilities, apart from the marketed board games scenario, are endless and I can't wait to get my hands on one!