Caffeine, besides being one of my favorite ingredients in coffee, is a very lightweight app that keeps your Mac from dimming the screen, going to sleep, or starting the screensaver. It lives a quiet, satisfying life in your menu bar.
It’s perfect for when the Macbook is running on battery power I but don’t want the display to dim or go to sleep. I’m happy to leave my sleep/dim settings where they are and use Caffeine to keep my Mac awake.
Get it here: http://www.lightheadsw.com/caffeine/
Created by: Lighthead Software
Rating: 8 (1=never use it again, 10=first thing I install on a new computer)