Given that this ONLY works on the iPhone 4 or 4S running IOS 4.3.3 or 5.1.1, it is going to be of limited utility.
But if that describes your phone (it does mine

) then there is a new app for jailbroken phones (via Cydia) that so far has increased my battery life enormously.
Works by switching off 3G whenever the phone is locked.
So far, I have had no issues and indeed the battery life has increased substantially
The app is akAuto3g
Google or read about it here, among others:
http://itechbook.net/how-to-disable-...henomenon.html