This is a project I did over the summer of 2005. A friend of a friend had this idea of selling a system to shops that would automatically pick and play songs from a number of directories, and the shop owner would be able to configure how much of each would be picked. E.g. 50% soft rock 25% country 25% instrumental.
As far as I remember it's pretty much working, but in the end the guy changed his mind about his business idea and I never saw a dime. Great lesson to learn at 22 :)