This Sixth Sense device ships a mini video projector with a gesture capturing webcam that let the user see (on his hand, on a wall, on a paper in front of him…) and command using predefined hand gestures, as illustrated in this video:
The Sixth Sense – created by Pranav Mistry from MIT – has also been presented at Ted here and there. I do like the idea, although the Sensics Natalia goggles bring both the HUD and the gesture input. Or, any smart glass having a camera (like Google Glass) will do so. And these goggles and glasses are also portable while not requiring a surface to project on.