Since most smartphones have bluetooth and a small accelerometer/gyro, when they get old or really cheap, they can be fixed to hands and legs as an input device for computer software.-- Ling, Jun 12 2012 The touchscreen could be used as well, and the screen (picture a 10x15 grid of Ipone screens, combined to make a monitor).-- erenjay, Jun 12 2012 What applications do you have in mind? It isn't that I don't mind carrying something attached to my limbs all the time.-- Inyuki, Jun 12 2012 I was thinking of those first person action games as one example. Then, running, jumping, crouching, handling of weapons would be maybe more fluid and double up as at least some kind of exercise.-- Ling, Jun 13 2012 random, halfbakery