This is the ultimate touch computing interface. It may only be a single pixel, but it is more capable than you might think. See it in action.

Jinha Lee's TED talk is one you need to see. Some of the ideas are obviously impractical, others are just not quite there yet; but nevertheless the overall impact is impressive. The thesis is that we are slowly getting closer and closer to our machines. From the keyboard, to the mouse and now touch. But this is just the beginning. Lee's work at the MIT Media lab has invented a pen that projects itself into 3D virtual space as you push against the screen - you need to see the video to get the idea. This might sound like just another virtual pointer but the transition from real to virtual might well trick the brain into a deeper belief in the VR than other approaches. 

The second big idea is the virtual 3D interface using an angled mirror. The user can see the 3D volume display and their hands and can manipulate the virtual objects. This isn't so new but the realization of a complete UI is interesting. It looks as if "gorilla" arm could be a problem with this interface as much as with using touch on a vertical monitor is. 

Next we have a wearable watch - classic AR - but done quite well. 

The final demonstration is what is really all about. Don't give up on the video until you see it. A single pixel interactive 3D interface:

The range of uses that has been found for this single "pixel" interface is almost as impressive. The next question is, could it be extended to a multi-pixel display and if so what use would it be? Perhaps you could shape a magnetic fluid or dust using a configurable magnetic field. Given how difficult it is to control a magnetic field, it seems unlikely. We have a long way to go before we get to the "hard" light holographic projector of Star Trek Voyager.