Basically have two QR code that is printed into a card/sticker etc... It has a sticky cover on top of it so people cannot snoop on the code before usage.
Upon theft/loss of card, you simply grab the nearest phone and have them scan either one of the QR code, (one is a url, and the other one is an SMS). It will then send a one time password to disable the card.
This process is much faster than calling the bank.-- mofosyne, Aug 01 2012 So, you keep the QR code on your person?-- RayfordSteele, Aug 08 2012 random, halfbakery