I saw a pilot lounge with a monitor that displayed a camera feed of the front doors so the pilots could see when their pax were arriving. Since I flew freight I always wanted a live camera feed of the gate so I could see when my truck arrived. It would actually be pretty cheap to install something like that.
Flightcraft in PDX used to have one. I was there a couple weeks ago and I thinks its gone. You could even move the camera around and zoom in on stuff. It was only for the ramp though
Get a pool table.