My friend found this trick somewhere, don't remember where. But the trick makes it so your phone doesn't search for 3G while in standby. It seemed to have worked for me. Won't really know until later on in the night. Right now i'm sitting on 74% after 8 hours. If this is old to you, then don't post about how you knew about this ages ago, its annoying and no one cares. Let me know if it helped improve battery life.
Instructions
1. Put phone into "Airplane Mode"
2. Turn phone off
3. Turn phone back on
4. Take phone out of "Airplane Mode"
Instructions
1. Put phone into "Airplane Mode"
2. Turn phone off
3. Turn phone back on
4. Take phone out of "Airplane Mode"