DPMS

DPMS (Display Power Management Signaling) is a standard from the VESA consortium for managing the power supply of video monitors for computers through the graphics card. The most common use is to shut off the monitor after the computer has been idle for some time.

For further information see Wikipedia:VESA Display Power Management Signaling

(Added by Ian Forde)

If you're using MythTV with a monitor and a remote (via lirc), it is possible to use DPMS to power off your monitor. Imagine the scenario where you're using Myth in a bedroom...

Let's say that you've got a Hauppauge grey remote, and want to use the red button for this. Assuming that you've got that button defined in /etc/lircd.conf, put the following into ~<myth user>/.lircrc

 # Red Button
 begin
   prog = irexec
   button = Red
   repeat = 4
   config = /usr/local/bin/monitorpowerbutton.sh
 end

Then you want the following in /usr/local/bin/monitorpowerbutton.sh:

 #!/bin/bash
 
 STATUS=`xset -q | grep "Monitor is" | awk '{print $3}'`
 if [ "${STATUS}" = "On" ]
   then
   xset dpms force off
 else
   xset dpms force on
 fi
 exit 0

Inspired by Jarod's power button trick for mythfrontend...