Take a look at OmniTouch which although still in the experimental phase aims to perfect a wearable system that enables graphical, interactive, multitouch activities on the surfaces that surround us. This shoulder-worn device allows users to manipulate the image projected onto walls, tables, objects and even their own bodies. The prototype uses a laser-based pico projector ( a Microvision ShoWWX) and a depth-sensing camera.
This raises some deep questions for me about how we will communicate with each other in the future. I mean, if pico projectors are to be integrated into Smartphones and Smart phones are rapidly becoming the repositories of our lives, it follows that rather than talking one day we might instead flash projected images to show what we're thinking rather than saying it.