Wallet Swells as Your Bank Account Grows, Shrinks as You Run out of Money

(Video Link)

John Kestner and other MIT students designed the Proverbial Wallet. It provides tactile feedback about the state of the user's finances. Whenever there's a bank transaction, it vibrates. As the user's bank account grows, it swells. As money is depleted, it compresses. A hinge tightens as the user approaches a financial goal, discouraging further spending.

Link via Gizmodo