Is there any simple way to switch off my pc's monitor? I can log in to my pc remotely.
If your logging into the computer remotely around the same time every day then you could try plugging the mains lead for the monitor into a socket with a timer. I can't find a pic off hand but it's basically an adapter that plugs into the mains and has a timer on it, which controls when the device plugged into it is switched on.
Not quite what I'm looking for. Is there any command I can run to power off monitor?
Possibly KVM over IP. Although obviously you would have to buy a KVM first.
Most monitors these days will go into standby mode automatically if they stop receiving a signal from the computer and will wake up again automatically when they do get a signal again.
Turning them off any further than that would stop the computer from being able to wake the monitor back up.
You could just turn the monitor off via its switch when the computer is on before you leave...no?
I guess that is too simple.