Amazon is the biggest online store in the world and undoubtedly has a big slice of the e-commerce market, so it makes sense that they have decided to launch its own currency, which is known simply as Coin. It is a virtual currency that consumers can use to buy apps and games on the line from one of the company's tablet, the Kindle Fire.The Coin launch will occur in May and it seems to only be available for the United States. Amazon plans to launch...