Adafruit Arduino Mega R3 Android Accessory Development Kit (ADK) Board - ATmega2560 ADK R3
Fast track your Android phone hardware development or just design cell-phone robots with the Arduino ADK! The Arduino ADK is a microcontroller board based on the powerful ATmega2560 (datasheet). It has a USB host interface to connect with Android based phones, and a power supply boost converter to charge up the phone from DC power while its plugged into the ADK
We are now selling the R3 version which has pin-compatibility with the MEGA R3 - there is now an IOREF pin and the duplicated SCL/SDA pins next to the AREF pin.
The Mega ADK is compatible with all of Android's Accessory Development Kit examples and also acts like the Arduino Mega you already love to use. It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. Now its easy to connect any sort of sensor, LED, motor, etc to your Android based phones.
The ADK is based on the Mega 2560. For information on using the board with the Android OS, see (Google's ADK documentation).