Is there anyway of turning off the LED screen on my MacBook Pro whilst using an external display?
I just go to full dimming, it seems to go off when you get to zero dimming (although there really is a slight faint image). Not what you asked but almost :)
Are you using an external keyboard? If so you can close the MBP lid and use the keyboard to wake the machine, it'll put all windows on the External display and your LED is nowhere to be seen.