In Time, a movie that comes out later this year starring Neil Cafferty, the Scarecrow, Leonard, Thirteen, and Justin Timberlake, looks like an interesting take on a cashless society in the future. At 25 years old, everyone stops aging and is given one year to live; they keep track of their remaining time via an implanted digital countdown clock in their forearm.
When it hits zero, they die. If they manage to add more time, they live. In this future, time is the new currency; a cup of coffee might cost 3 minutes, and if you can amass enough time, you can live for hundreds of years. Obviously, only the very rich get to do so.
It looks like an interesting take on the whole problem of solving aging and what we would do with the ever-increasing number of undying people. I might see it in theaters when it comes out at the end of October.