Rewards Card App

  With many chain stores now having "rewards" membership cards, it is becoming a hassle to search through your wallet to find the right one, especially if you are at the checkout with a line of people behind you.
My idea, that as far as I know does not exists, is a "smartphone" app that would contain all of your rewards/wholesale club membership cards. This app would already link your information with all the stores that you are a member of and frequent, eliminating the need for a plastic card.