Great idea I reckon. A camera on the vertical stab looking forward (like currently on 777/A340 family and newer), a camera on each wing sharklet/winglet looking inward at flight controls and one or two on the rear position light looking down at elevator stab. You would be able to determine things like if you had an engine fire or wing fire, condition of flight controls after malfunction or fire (calc of an abnormal Vref if flap burnt through), or which side to call exiting for an evacuation (yup the cabin crew should assess exits prior to pulling slides but it all helps). It would be an effect tool to help save lives at little cost.