This week Dynamics is showing off a new credit card that can rewrite its own magnetic strip on the fly. So you get a card that you have to punch in a code before it can be swiped or before you can read the credit card numbers. After a few minutes, the information erases and it returns to being an inert piece of plastic. Or, for the convenience factor, a card can have multiple credit cards on it. Just push the button of the card you want to use. The future is here and its in your wallet.