You might have heard of Bitcoins, the digital P2P currency unbound from the constraints of governments and stock markets. It sounds like a cool scifi idea, but what are you supposed to do with Bitcoins? Until now the answer was “not a whole lot,” but a new service gives Bitcoins users an easy way to cash out by trading the currency for Amazon gift cards.Bitcoin was created in 2009 in the wake of the global financial collapse. It doesn’t operate like traditional currencies — there is no central bank that oversees Bitcoin. Bitcoin transactions are managed by the distributed computing resources of so-called miners. Miners can generate new Bitcoins at a set rate that will be continuously ratcheted down. As such, the supply of Bitcoins is fundamentally limited. No stock market trickery can magically generate more of them.So let’s say you’ve generated or, more likely, bought some Bitcoins. Most shops and websites aren’t set up to accept Bitcoin payments, but AmazonBitcoins offers an interesting option. All you have to do is sign up for a free account and ship some of your Bitcoins over. In return you’ll get a $25 Amazon gift card.Each account gets a unique address to which the payment should be sent. This address is a long string of letters and numbers, so you’ll want to copy it exactly. For each 0.573 Bitcoins sent (as of this writing), you’ll get an Amazon gift card emailed to you. The transaction takes about an hour to complete.0.573 might not sound like a lot, but each whole Bitcoin is worth somewhere in the neighborhood of $46. So when you do the math, you’re not really paying a premium for the Amazon bucks. The folks behind this site are clearly expecting the value of Bitcoin to continue going up. Risky, considering it’s been a rough ride for Bitcoin so far. Still, through all the ups and downs, it’s only getting more popular.