Mi Suny Phone Charger
Not only has an internal battery for that extra juice available, but it also can be charged via the USB cable or the solar panels on the back of the case. There's no way you are going to run out of battery again!
Case Mate ID Holder
Forget about your wallet! You can carry your phone plus some credit cards/ID with the Case Mate ID Holder. Made of a slim profile, impact resistant shell, the Case Mate's snug fit will ensure your cards won't fall out of place.
The Beamer ($32) is a hard plastic case with a built-in light. The light is battery powered, so it won't drain your phone's battery and will stay on for up to 10 seconds at a time. It's perfect to use it as a light for your phone's camera unless you have an iPhone 4 with a built-in flash), or just as a flashlight to find your keys in the dark.
Richard Solo 1800
The Richard Solo features a built-in LED flashlight and a laser pointer. Also, the 1800mAh capacity battery is good to keep your iPhone juiced up for a long time. Too bad is not built-in into a protective case and rather is an add-on via a cable to your phone.
For $39, you are going to get more than a protection for your iPhone. The Opena Case adds a beer bottle opener to the end of the case. The stainless steel bottle opener slides out of the back of the case, so you are only a few seconds away from your favorite cold one.
Another option could be: