If you're looking for a method of capturing external data from sensors and user input into an Android application, the notes published by Australian enthusiast David Baker may be of interest. He shows that an Arduino Leonardo-compatible board such as our LeoStick can send serial data directly to an Android device (in this case a Samsung Galaxy SIII) via a USB on-the-go cable. Currently a work in progress, however demonstration Android code has been provided.
So what is a LeoStick? It's the Arduino Leonardo-compatible board that's cheaper and smaller than the original:
Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo which can be used a knock sensor and various tune and sound effects. Plus you can add extra circuitry with the matching protostick! For more information and to order, click here.