Juice defender comes to mind. If you are keen on some experimenting then I would reccommend Tasker. It is a great app that sets actions based on contexts. As an example you can use it to perform the same funtion as juice defender (only allow data for 2 minutes an hour) or only turn on GPS when using Maps or navigation and turn it off automatically. You can automatically enable wifi at home and disable it once you leave home.
I used JD for a while, my phone switches to wifi automatically when i'm at home, however with online gaming I switch it off, but for some reason JD switches it back on again. I can be completely wrong and it is not JD's doing.
but will give this Tasker n try. tnx