Micro-sensors are making a lot of progress these days. MIT, Berkeley, Carnegie Mellon and many others are moving the ball forward thru collaboration much faster than would have been anticipated. The number of applications is staggering. Some is simply fun and games while others have great ramifications in medicine, robotics, military, space and institutional instruction. Virtual Keyboards, smart dust:

http://robotics.eecs.berkeley.edu/~pister/SmartDust/

Student have been using them under their finger nails to count cards in the CT Indian casinos and the sensors are wired to their watches, displaying the results, pretend I did not tell you that. I refuse to reveal sources. Each time certain cards are played they tap out with their fingers on the table, using certain fingers for certain numbers such as 1