The PowerSkin for iPhone 4 ($80) is a silicone case with a built-in rechargeable 2,000 mAh battery that claims to double your device’s battery life with patented “XPAL Power” battery technology. Like most battery cases, it uses a mini-USB port to charge and sync your iPhone simultaneously, and you can turn the case on and off when necessary. The four-LED battery indicator will let you know how much juice you have remaining at the touch of a button.
PowerSkin for iPhone 4: The Electric Surfer [Review, Battery Case Week]