Wow. Now this is interesting. A company called Walletex has finally come up with a real "credit-card sized" USB drive, that really, truly looks and feels like a credit card. Meaning, it's not just rectangular and kinda thin. The Wallet Flash 1.1 is being touted as the thinnest USB drive on the market and as you can see, it's easy to store. Right now, sizes are 128MB ($29), 256MB ($49), 512MB ($89) and 2GB, which isn't priced yet.
2GB Credit Card Shaped Storage [Trusted Reviews]