Added a new extension:
Allows for doors that are implemented as having independent ‘faces’ — to put a knocker on that can only be seen from on side, for instance, or to allow the player to lock one side with a key but the other with a latch. Also introduces a ‘latched door’ kind.
Emily Short's Interactive Storytelling 
Or to make a one way door peep hole like the ones you see on Hotel doors.
Have you done that? It didn’t occur to me to try it, but it’s a cool idea.
I haven’t written any games yet but I always seem to come up with things I think would be neat to have in a game.