Peter Schiff: The rise of the barter economy

Another variation, from a group based in Phoenix, Arizona, encloses a pre-1965 US dime inside the laminated card. Before '65, every dime contained 90% silver, making them worth about $2.50 each in today's debased dollars. That's why you won't find any pre-'65 dimes in your change from the grocery store. However, one fellow had the clever idea of putting them in these cards so they could trade at their silver value without getting mixed in with the worthless dimes we carry around today. The same group even created a free iPhone app that translates US dollar prices into various amounts of silver (more info here).