How much technology can you fit into a 0.8-millimeter-thick credit card? Last November, Coin offered a first taste of what was possible. The device promised to digitally hold eight credit or debit cards and let you choose between them at will. You could swipe Coin in any conventional card reader, and it would notify you if it had been lost or stolen using Bluetooth. Coin would have a two-year battery life, and a companion app that could hold your coupons and ID cards. But Coin still hasn’t shipped.
