I just got my extended battery, but had one problem. I like having the extra juice but it left my phone naked and vulnerable. Here's my solution:
What you need:
1: The Sprint body glove case. can be found
Here
2: a dremel
3: a steady hand
It's real easy, can be done in less than half an hour. All you need to do is take the back of your case, and press it against your battery so you have an imprint of where your battery is at on your phone. Then you cut through the plastic, LEAVING THE RUBBER BACKING IN TACT. This is what will hold your battery in place. Make sure you cut just outside the imprint of your battery so you give the backing enough room to stretch. The outcome was a lot better than I expected.