1) Change the battery polling to 20000.
http://forum.ppcgeeks.com/showthread.php?t=39966
2) Download the toggle 1x cab. (I just did that today. Thank you to intx
)
http://forum.ppcgeeks.com/showthread.php?t=86819
Those are just 2 for now.
I will post links in a short while.
You can Search in the interim
Here's some more >
3) You can program your "Long Press Key" to disconnect data.
There is also a registry change to end data in 60 seconds when idle.
I don't use that registry change because it can take more battery power to toggle on and off at 60 second idle intervals if you are often in and out of data sessions. Now I can manually end it whenever I want to.
If you are not in and out of Data sessions constantly, the Registry change can be very helpful and you would not have to manually end a data connection as I do.
See this thread for the Data Tweak and much more >
http://forum.ppcgeeks.com/showthread.php?t=36865
4) As was already said, LUMOS is a really nice application, and can reduce battery usage.
http://forum.xda-developers.com/showthread.php?t=450318
And finally, take a look at Diamond Tweak >
http://montecristoff.webs.com/
All this should keep you busy for awhile, and help your Diamond last a long time
Don't forget to "Thank" the Developers for their hard work in finding out how to Enhance the Diamond.