I basically have two streetlights on display. xD One is my OV-10, which is one of the actual LIGHTS that light up my room down here, and the other is still my M-400 R3, which I can turn on whenever I want by a switch (on a power strip) next to my desk-table-thing. Funny thing is the OV-10 uses a higher wattage lamp then the M-400 R3, but different lamp types, so yeah. OV-10 is incandescent and the M-400 R3 is HPS. But yeah. It's nice to have lights on display.
Yeah, it makes room for more lights and it gives you the chance to show off the collection's finest. I used to have two displays too, the one in my room and the one outside, both of which were operational. The one outside was taken down and I will be getting a new one, probably in the spring or summer next year.