This is very similar to a blog post I wrote a year ago. My idea was to use a barcode to capture someone's information which normally would reside on a plastic card like a frequent flyer card or preferred shopper card. The card would "live" on one's iPhone and could be used in-store instead of the plastic card.
The actual digital card could look quite similar to the real plastic card and have the same dimensions but the barcode would provide an extra layer of authenticity. - Timothy Post
