It already exists.http://www.visa-asia.com/getacard/Visa_Mini.shtml

Do away with the card altogether, have your personal barcode tatooed on your face.

Just what we need more stuff to put in cell phone case that will fall out when you take your cell phone out to make all your calls when driving now still while driving having to pickup the credit cards--SPLAT goes another cell phone user not looking where he/she was driving--Cell phone use while driving should be same as DWI both are impaired!!!!!

What the hell is cellphone case?

A Cell phone case is basically a protector container to put your cell phone in. Most are made of a faux vinyl leather, with a PVC window, and allow the phone to be used in place. A few require the phone be removed to be used.

As for half sized credit/debit cards, doable, but probably not practical now.

We (at least North Americans, are beginning a transition from magnetic stripe payment terminals, which require a full length card, to ISO 7816 electronic cards, which require full width cards. They need to be full sized (ISO 7810) to work in most ATMs or self service payment terminals.

Other cards can be, and are reduced size, but retain a full magstripe, barcode, or are a form of RFID.

Bank of America had one with a keychain hole, and Discovercard made one that folded like a pocket knife. Neither really caught on, probably due to the stares of other folks in the checkout line.