Right now you can get the uNu iPhone 4/4S Battery case for $19.99 from Woot.com. This is selling for $34.99 on Amazon right now.
This case actually charges your phone for you!
This is super neat. If you are anything like me, you are constantly having to charge your phone…this backpack up case should give you a bit of a reprieve.
Here are the specs:
- uNu battery case is designed to virtually double the usage time on your iPhone while still protecting it from hazards
- Compatible with all versions of iPhone 4 and iPhone 4S
- Built-in Battery + Protective Case + Signal Problem Fix
- Invisible charging switch, simply touch for 2 seconds to toggle on or off
- Slim form factor and anti-slippery finish
- Apple Certified 30-Pin Connector
- Smart Switch, gain more control over charging to enhance safety
- Accurate LED power indicator, flashing when battery runs low
- Included micro USB cable can fully support charging and computer synchronization with the case installed on your iPhone
You will need to pay a flat rate $5 for shipping.