His concept (this is only a design; it's not even a prototype) uses what appears to be an iPod-like interface to choose between different accounts. It has a display that constantly updates you on your financial health.

The wireless device uses biometric security to make sure that you are the only person who can use it. It also provides you with a forecast of your financial future, based on the purchases you are about to make (see additional photos).

I don't know of an earlier description of the credit card than that provided by Edward Bellamy in his 1888 story Looking Backward:

A credit corresponding to his share of the annual product of the nation is given to every citizen on the public books at the beginning of each year, and a credit card issued him with which he procures at the public storehouses, found in every community, whatever he desires whenever he desires it. This arrangement, you will see, totally obviates the necessity for business transactions of any sort between individuals and consumers. Perhaps you would like to see what our credit cards are like...
(Read more about Bellamy's credit card)

This idea is modernized somewhat in the credit card used in Neal Stephenson's 1995 novel The Diamond Age:

If they accepted you, they'd shoot the credit card right into you, then and there, on the spot. These guys implanted it in the iliac crest of the pelvis, some opted for the mastoid bone in the skull... Then you could go around and buy stuff just by asking for it... (Read more about the implanted credit card

As it happens, this kind of implanted card is already being tried; there is a Baja Beach Club Implanting VeriChip In Customers. The VeriChip is a RFID tag small enough to implant just under your skin; it accesses the Veripay payment system.

The ultimate expression of credit cards might be the universal card used in the future worlds of Dan Simmons' 1985 novel Hyperion.

If our society ever opted for Orwell's Big Brother approach, the instrument of choice for oppression would have to be the credit wake. In a totally noncash economy with only a vestigial barter black market, a person's activities could be tracked in real time by monitoring the credit wake of his or her universal card...
(Read more about Simmons' Universal Card)

Interestingly, if you try to consult any of the credit card industry oracles, the only really new thing they see on the horizon is the contactless smart card that uses RFID chips and merchant RFID readers to let you just wave as you walk by with your purchases.