I've several times wanted a shortcut for turning off my monitors, as my default time for my screen to go black / dark is set quite high.
TURN OFF LCD
This little program can help: Turn Off LCD.
I have to say that I have not seen the source code of this program. And running .exe files you are not 100% what does is not very wise. What lifehacker writes doesn't make the code safe either. That aside, I've been using this on one of my machines for a while now.