In System Settings > Wireless & Networks > Mobile networks, you can turn on/off 3G without needing an extra app to do so, so as to save space on your phone for something else.
Also, use JuiceDefender, and customize it to your needs. I gained six hours with JuiceDefender alone, and that was way before I learned what Rooting was. Additionally, many of the available ROMs come with extra/longer battery life as standard just based on app cleanup - which all of them have - alone. In lieu of other changes that may also increase battery life.
EDIT: Also, Power Toggles is nifty. And never use the wifi hotspot. Ever. There are rooted apps for this that do work, but the built-in feature does not.