Making your computer consume less energy is a no-brainer. There are three things that you can do:

1. Energy management. Adjust the sleep-time for your screen, harddrive and system.

2. Screen saver. A nice screen-saver like Pixel Breaker makes it less annoying everytime your computer goes idle.

3. Shut down after work. Many people, especially at the office, leave their computers on all the time. Sometimes by habit, sometimes for system backup reasons. At our office, we have set the backup schedule to run during office hours instead.

Part 1: The principle
Part 2: Less sparkling water
Part 3: White glow