Not an extensive list, but some simple ways I can think of off the top of my head. ;-)
1. Switch off monitor when not in use.
2. Put system to standby when going for lunch.
3. Set shorter screensaver duration.
4. Use different power saving options, especially for laptops.
Terence
"If each grain of sand were to say one grain does not make a mountain, there would be no land.
If each drop of water were to say one drop does not make an ocean, there would be no sea.
If each grain of wheat were to say one grain does not make a paddy, there would be no harvest.
If each of us were to say one person does not make a difference, then there would be no love and peace."