Get rid of the app killer. It runs in the background and eats more battery than it saves.
When you exit apps, try and see if they have a menu option to "Quit" rather than just hitting the "Home" button. Hitting "Home" can leave an app still running.
GPS doesn't seem to eat much battery at all. Make sure you've also got 4g off, your sync's to things like Mail, Facebook, Twitter, etc... are set to sync "every four hours", "once a day", or "never" instead of constant.
Adjust your screen brightness manually and keep it at a low setting.
Just so you know, there's a lot of other threads out there about this kind of stuff. Just do a search on the forum. For what it's worth, the battery life isn't as bad as some reviews state. There's also an extended battery coming out in a couple of weeks for those who want uber-battery life.. and finally, if your battery does run low, you can swap it out for a fresh one, whereas in an iPhone, you're left having to merely sit and charge your current battery.