Hack the MintChip challenge.

The Canadian Royal Mint is doing away with boring old currency in favor of "MintChip," a digital alternative to bills and coins. It aims to go beyond mobile payment options like Square or Google Wallet, instead offering an entire platform of digital currency. It will basically serve as a virtual wallet, and will exchange Canadian dollars securely so the amount will be added onto a chip, which can then be fitted into microSD cards, USB sticks or systems inside stores. The value can be transferred in between chips and will be added to the chip by a "broker."  

Sounds like a dessert, but the Royal Mint is actually offering cold, hard, gold ($50,000) to software developers that will successfully think of a way to integrate the payment system into apps and smartphones.

The Mint has already developed prototypes and pending patents. It plans to make it anonymous, with no central database that would record transactions. http://creativity-online.com/work/royal-canadian-mint-mint-chip/27198