The most immediately practical "good idea" I came across was from guys who had laminated a business card containing a US pre-1964 dime. On the back of the card is a table showing how much silver such dimes and quarters contain, and what their market value was when silver was $30/oz. What was really neat is that there is a phone app to help you keep track of your silver coins, and they also came up with the refinement of putting advertisements on the front of the card.

The beauty of this approach is that the government can't possibly pull out the von NotHaus charge, claiming that people producing such "dime cards" are counterfeiting US currency. Of course they're not — they're just providing a convenient package for US currency. I was reminded of this when I threw a handful of the dime cards in my bag, and then wondered if TSA would give me trouble. How could they? I'm just carrying a bunch of dimes in my bag.