Leave it to students at the MIT Media Lab to develop a wearable computing system that turns any surface into an interactive display screen. With an ordinary webcam and a battery-powered 3M projector, they attached a mirror and connected it to an internet-enabled mobile phone. A mere $350 of off-the-shelf components and suddenly the glass window at Macy’s, your car door, or your arm become a computer display. Want to Google the latest Dow Jones, Nasdaq, or S&P 500 returns? No problem, just do a quick search on your shirt sleeve.