I have exactly zero stats to back this up, and it's probably just wishful thinking, but
jupiter (hardware and power management tool) seems to have improved my battery life (Thinkpad Edge). See pileofrocks's comment below.
If you want to try it out
Press Ctrl + Alt + T, terminal will pop up; type
sudo add-apt-repository ppa:webupd8team/jupiter
enter password (you won't see it as you type, that's normal), confirm adding the repo, then:
sudo apt-get update && sudo apt-get install jupiter
If you want to play around with settings yourself search for
jupiter in the dash.