Look at sedio's extended life batteries. Theses aren't cheap but they last a lot longer than the oem version and they all come with a replacement battery panel, that is also better than oem. There are reviews of these batteries on this forum, you just have to search.
The first is a Slim type extended battery
I actually own this one. The battery life is pretty good. It last maybe 1 or 2 more days than the oem version.
Second is the Large extended battery
. The one I should have gotten.
From what I've read this battery last a really long time and also makes the phone easier to hold.
They also sell holsters and cases that fit these new batteries. I hope that helps.
P.S. You really wanna be careful when changing out the battery. I've personally seen the latching mechanism on these phones break rather easily. Some of my friends have had problems with this issue.