When working on an other project (CastDuino), I found out about the limitations of the Arduino hardware and it almost made me quit the project. I2C came along and that was the solution for my problem, why not using 2 Arduino's in 1 project.
Because Arduino's aren't really cheap (now you can find cheaper ones), I started wondering if I wouldn't be able to make on myself. Well here you have it.
All you need to do is connect the wires for I2C (if you to connect it to an other Arduino and GND and +5v. Your master Arduino will regulate power, so you don't need that on the BBA. You could also run it from an USB cable plugged into your computer.