At PAX 2012, we got a chance to look at MOGA, a portable gaming accessory for Android 2.3+ based smart phones and tablets. It's designed to be a mobile controller that enhances a users ability to control the game by adding two analog control sticks, classic gaming button functionality, and shoulder triggers. It connects to your device using Bluetooth and secures your device using a very grippy retention system. The retention system can expand up to 82mm to accommodate large devices like the Samsung Galaxy Note, meaning pretty much any Android smart phone is compatible with it.
PowerA works directly with game developers to make their games MOGA compatible, and once a game is made to be MOGA compatible, it's available for all versions of the game. This means that the device doesn't utilize a configuration software or require users to fumble with mapping game controls to the physical controls. To make your life even easier, PowerA has developed an application designed to centralize all MOGA compatible games called Pivot. Pivot allows you to browse MOGA compatible games, direct you to download them, and then launch all the MOGA games you have from one list.
It would be better with additional battery for your phone with universtal USB connection