Rock concert lighting! This is a freaking amazing addition to your KISS, ACDC, MET or the upcoming Aerosmith pin. These are called Moving Head Lights. I bought this pair off ebay for $115. These are sound activated, synchronized and move in unison in a variety of preset patterns and colors. You will need an XLR microphone cable to connect them - not included but easy to find at your local music store. They are programmable with an additional controller. Very, very cool.
I borrowed this idea from another pinsider (robertdwinter) but it didn't find a lot of information on where to find these. If you search for moving head led light dj dmx-12 then you'll find lots of them. The ones I bought are from Lixada but these are sold under several brand names for about $60 each.
Combine this with modding the songs through Pinball Browser and you get a kick butt rock pin experience. When I get Demon Multiball going with a little Boston Smokin and the lights are going crazy it's a full on assault on the senses!