Plastc Card could replace every card in your wallet.

Plastc Card is a credit-card sized mini-computer that stores up to 20 credit cards, debit cards, loyalty cards, access cards for doors, and more, so that you don't have to carry all of them individually. Take a look:

According to the FAQ:
What type of cards can I store on my Plastc Card?
Your Plastc Card can store many types of cards, including loyalty cards (even cards with only barcodes), store cards, gift cards, debit/credit cards, and even access cards.