South African Airways had (may still do) multiple external cameras on their aircraft, and they were even viewable from the In-flight Entertainment System.
I thought it was neat both from the perspective of pax and pilots.
If I recall correctly, there was a tail mounted forward looking camera. that got both wings in, a belly mounted forward looking camera that got the forward landing gear.
It was a long time ago I last saw it though, so I stand to be corrected.
Birrddog