Starting in May, Kindle Fire users are going to have a new way to purchase content. Amazon Coins, announced last week, are a new virtual currency for U.S. customers to use to buy apps, games and in-app items on Kindle Fires. The Coins system seems to be bucking a trend, as similar payment methods in the tech world are being eliminated, not created. Facebook introduced Facebook Credits in 2011, only to eliminate the system a year and a half later. Microsoft seems to be doing the same thing with its Microsoft Points on the Xbox 360. But for Amazon, it hopes the Coins system will get Kindle owners excited about buying more apps.  As an incentive, Amazon will give away tens of millions of dollars in Coins to existing Kindle Fire owners when the program launches. Are Coins really going to make you a loyal Amazon customer, or will they just annoy you?