Firstfives.org

Some E30s, E28s and E23s had an interior rear-view mirror with integrated map lights. BMW p/n 51161906525, which is NLA but I picked one up from an E30 part-out. You run power up the A pillar and along the headliner to the mirror, and the base is the same as the E12s.

It's more convenient than the side-mounted courtesy light, especially for the passenger.

Ive been keeping my eye out for one of these for some time now. Let me know if you see another one float by.