A wearable system called OmniTouch turns an ordinary surface like a table or the wall in front of you into an interactive multi-touch input device. Researchers Hrvoje Benko and Andrew Wilson from Microsoft, and Chris Harrison from Carnegie Mellon University came up with the prototype that combines a projector which projects the touchscreen onto a close by surface or body part, and a camera which tracks finger movements. The shoulder-worn system may be an alternate approach to mobile interaction leveraging everyday surfaces with no calibration required.
Read more about OmniTouch here:
http://research.microsoft.com/apps/video/default.aspx?id=155040