In my desktop-environment I use a lot of partly-custom-made commands and scripts to improve it’s usability. Some things are really useful for everyone, so I’ll share them here.
The first one I present is a command which shut’s down your screen after one second. If you move the mouse or press some key it will wake up again. The one second delay is therefore some time for you to get your hands off your computer.
sh -c "sleep 1; xset dpms force off"
Another one aims in the same direction: use xlock to lock your screen and shut down the display.
xlock -mousemotion +description -mode blank -bg black -fg white -remote -username 'Username: ' -password 'Password: ' -validate "Validating..." -dpmsoff 1 -startCmd 'xset dpms force off' -info 'Insert password to unlock the screen'
man xlock for more information.