OmniTouch by Microsoft ResearchI’m quite interested in the field of wearable computing, especially as I see it relating to the next logical evolution of computing beyond mobile (hardware). OmniTouch is something that I came across while reading. Its a good bit bulky, but does enhance the spatial relationship people can have within computing interfaces.
I also am reminded of seeing something quite similar done with the Nokia N95 smartphone a number of years ago. Nice how history repeats itself, but finds ways of being reinterpreted in another toolset for additional learnings.
blog.arjw 
I think that the projection device would have to be smaller for it ever to be practical.