There is provided an accessory device for a financial transaction token. The accessory has an onboard power storage device that enables a financial token or card that is in communication with the accessory to operate when the card or token is not in the proximity of a merchant terminal (e.g.; a POS terminal)....http://www.google.es/patents/US7819321?utm_source=gb-gplus-sharePatente US7819321 - Appliance for financial transaction tokens
