The other day, I was talking to a coworker about music, specifically something he believes to be true (and I have not moved to confirm or debunk), that Disco was generally 132 beats per minute, in order to facilitate blending, because variable-speed turntables were hard to come by in the 70's. That lead to a discussion of turntables, including my mentioning that I still have and use one.

To begin with, this is, admittedly, not very scientific, but it is neat.