I have tried XDA's root method for increasing battery life, and have gotten mixed results. I have also tried the non-root method of charging it all the way while it's on, then turning it off and letting it charge for another hour or so. As I usually charge my phone at night, this is very difficult. I have a solution which has been working like a charm for me. I use the app Reboot Manager/Widget from the market and it's amazing. I set it up to shut off the phone at 4:15 AM every morning. It almost doubles my battery life! It is the only app that I have purchased and it is DEFINITELY worth it. Try it out for yourself and post your results.
