This is a bit of a rehash of a larger article I wrote months ago highlighting my main Autohotkey scripts, but I saw in the search stats that some people were specifically looking for an autohotkey script to put one's monitor on standby.
Here it is, the way that I use it. It puts the monitors on standby by hitting Win+M:
#m:: ; Win+M hotkey that turns off the monitor.Don't ask me for a line by line explanation more than what's already annotated in the script itself; I have no idea.
Sleep 1000 ; Give user a chance to release keys (in case their release would wake up the monitor again).
; Turn Monitor Off:
SendMessage, 0x112, 0xF170, 2,, Program Manager ; 0x112 is WM_SYSCOMMAND, 0xF170 is SC_MONITORPOWER.
; Note for the above: Use -1 in place of 2 to turn the monitor on.
; Use 1 in place of 2 to activate the monitor's low-power mode.
I can't find the original Autohotkey forum post in which I found this specific script, but this forum post has more info.
p.s. - for those of you not in the know, Autohotkey is an extremely versatile program that lets you write scripts as simple as automating windows tasks (like moving a mouse, or opening a folder with a keystroke), to writing full on programs and mods.