Amazon unveiled its Mobile Associates API this week in a bid to prompt mobile developers to hawk its physical goods in their apps and games. Do that, and the e-commerce giant will give up to 6 percent cut of the sale. The API, which works with Amazon's Kindle Fire and Android devices, allows developers to sell a single item within an app or game, showcase a category of goods or bundle a purchase of a physical product, like a toy cannon set, with a digital one, like a game.  Amazon's API could provide additional revenue streams for developers by allowing them to extend beyond their traditional approaches of charging to download an app, offering freemium models where digital assets or subscriptions are purchased, or loading up on mobile advertising. Participating developers can offer their products in Amazon's Appstore or Google Play. However, using the API it doesn't mean you'll strike it rich. Integrating a physical purchase into a game means you'll have to stop game play. Buying assets to pump up a score, to buy a book may be another. On the other hand, a developer using the API could, for example, offer a nutrition and fitness app which enables users to buy vitamins or fitness gear directly from Amazon.com. If done correctly, offering in-app purchases can be lucrative. One popular social media and app developer, Hong Kong-based Onoko International, found game companies do exceptionally well when it comes to encouraging purchases within a game without realizing how much money they've spent.