Wallet Card

A card that can be used as a wallet to pay with by adding funds by the customer at the store (offline) or by credit card (online) or other means which can also have an API for automatic balance update when the payment is made online. The store can also set its own currency symbol to show up on the card balance and letting him to choose where he wants the currency symbol to appear, right or left of the balance. Its a bit like the concept of the certificate card needing some tweaking.