If you're using a Linux-powered laptop with limited battery life, or you just want to darken your laptop screen for whatever reason, Tombuntu has a tip for you. To turn the monitor off and have it wake up at the touch of a mouse or key, create a shortcut using this command, or type it into a terminal:
sleep 1 && xset dpms force off
(Note: The "sleep 1 && " portion is only necessary for terminal commands). Any laptop can be set to darken its monitor after a certain amount of time, but even the quickest setting—15 minutes on mine—uses precious battery life if you need to look away. Adding this shortcut to a panel button or menu could come in handy.