IOD: Use for Rollable display in Check Cards

At CES Philips showed another non-production demo of Rollable display technology. Sure, I'm excited that our devices will keep getting thinner, but I'm more excited about other potential uses.

What about putting a 2"x2" rollable display into the front side of check-cards in the future? The display could show you your current balance and let you browse the receipts for your last X purchases.  All you need is a slightly more advanced smart card and a thin power supply to make it a reality.  Just my crazy idea of the day.

What would use use super thin/flexible displays for?