The Shopify Mobile Buy Android SDK by Shopify aims to simplify the selling of physical products from a mobile application. Download includes Mobile Buy SDK for Android and a sample app to know how to use the SDK. Requisites include SDK 9, JSK 1.7, Android 1.2.x, and the mobile app sales channel to the Shopify store.
It's come a long way from the Sears and Roebuck mail order catalog. Yet, the new API might bring wrench and dishwasher company Sears the closest it's been to its origins in decades. Developers can now search the entire product database of Sears and Kmart (the companies merged in 2005).
Revel Systems API makes it possible to run a cash register, a restaurant and a mobile point-of-sale system with an iPad as the center of the user interface. Check out what Revel has to say about the API on their website.