One of the iOS hacker @xvolks has released a tweak via Cydia called BattSaver which claims doubling down your battery life by switching off the functionality on your iPhone when not in use. Once you have enabled the tweak, it would work in the background efficiently in order to 2x battery life. It also includes monitoring views to deal with battery state in real-time. So everything you need to know is shown to you inside the application.
iPhone is the only smartphone in the market which manages the battery life efficiently. However, if 3G is enabled from settings.app, the battery would start draining much faster. In fact, even if you are in zone where you could use Wifi, 3G would remain turned ON which is not at all good for making the most out of your battery life. If you had been looking for a solution to solve this issue, look no further and install this tweak right now. 
BattSaver has priced at $2.99 which is not much for people who need a proper remedy. Although we haven’t given it a shot yet, but we have no doubts for the developer. @xvolk is the one who had a tremendous contribution in the development of Corona (an easy way via Cydia to untether iOS 5.1.1 JailBreak). Have you tried already? Let’s know what do you think about it in comment section.
PS: Please note that iPad and iPod touch are not supported. It’s meant only for iPhone at the moment.