I seem to always be running out of power on my iphone, now I dont have to with the PowerSkin Case. The slim fit cases offer protection for your phone and can double your battery life… They are made of impact resistant silicone, lightweight, non-slip grip, and flexible. Your batter life will extend from 4.5-8 hrs.
Find it Power Skin
They are available for the iPhone 4, Samsung Galaxy, HTC HD7, HTC Evo, myTouch 4G, Samsung Vibrant, and many other Smartphones.