If you watch the end of this video http://www.ted.com/talks/pranav_mistry_the_thrilling_potenti... which was posted on HN a couple of days back, you will see a lot of things that he proposes which can completely change how we interact.

He not only gives an example of virtual keyboard, he also gives example of a paper can be converted into a touch screen with a motion sensor.

Highly recommended video.