With laptop battery life, I'll take any help I can get. The clearest sign that my MacBook Pro ($850 at Best Buy) is aging is the unavoidable fact that its running time continues to evaporate, if not day after day then month after month. It just doesn't hold a charge like it used to.
Powering the display is the biggest drain on battery resources, so I keep display brightness at a minimum (it's also easier on my eyes) and use Energy Saver settings to slightly dim the display on battery power and turn off the display after 5 minutes of inactivity. Powering the keyboard backlights is a lesser drain on the battery, but there's a built-in setting that I recently learned about that turns off the keyboard backlights after a period of inactivity too.
Keyboard backlighting auto-shutoff
You won't find the keyboard backlight setting in the Energy Saver panel in System Preferences along with the display (and hard disk sleep) settings. Instead, you need to go to System Preferences > Keyboard. On the Keyboard tab, check the box for Turn keyboard backlight off after ____ of inactivity. Your options range from 5 seconds to 5 minutes. I chose the middle selection of 30 seconds.
Not only does this setting help my battery run a bit longer, but I also like the effect of the keyboard backlights turning on when I tap a key to resume my work. I enjoy the greeting of my MacBook lighting up and springing to life when I return to it -- similar to my dog wagging her tail and running circles around me when I walk through the door after having been gone for 5 hours or 5 minutes.
(Via OS X Daily)