Amazon CoinsAmazon today announced it'll use its own "Amazon Coins" as a virtual currency for purchasing apps and in-app purchases on the Kindle Fire. The currency system will debut in May, and Amazon says it'll give customers "tens of millions of dollars' worth of free Amazon Coins" to jump-start the economy. (Insert stimulus package jokes/groans here.)

One Amazon Coin is worth 1 cent. They'll only be available to U.S. customers at launch, and they can't be used for subscriptions.

The usual rules apply, Amazon says, in that developers will still get 70 percent of the revenue when users make a purchase with Amazon Coins. There's a small catch, however -- developers need to have their apps submitted and approved in the Amazon Appstore by April 25 to be ready for Amazon Coins at launch.

Sources: Amazon Coins; FAQ