Here’s what it sounds like: http://www.youtube.com/watch?v=gwvnS1mqX78
it uses a 12″ (LP record) film disc, with 57 concentric tracks of optically-coded audio (very similar to 16mm movie film).
The good part is that many of the pre-recorded disks sound delightful to modern ears, and the equipment is much easier to maintain than, say, a Mellotron. The bad news is that the players are pretty low fidelity, and players and media are hard to find.
The community: http://optigan.com
Mark_Frauenfelder
It also reminds me of a fun music-making app called Loopesque
