auto disconnect is a night and day differemce for me
2g 3g switcher is handy if your 3g coverage isnt so good, use in conjunction with auto disconnect
simple brightness app is good, turn the screen brightness down from the status area makes a bit of a difference i guess
titans kernel for power users is good, I under volt mine using lv and clock it from 250 to 950 and get great battery life, read up on overclocking first if you decide to do it
use xterm and run the command 'top' to see what your processor is doing, you may have an app thats eating your battery
turn wifi search to never, that makes a difference
dont use animated backgrounds, service provider changer or any gimmiky thing that runs in the background, no offence to any developers of such apps
get a spare battery and keep it in your wallet, car, somewhere you'll need it not an app but still helpful