If you know a couple of professional musicians, you're probably only two or three degrees of separation from almost anyone else in the music world. For example, I know the guitarist for The Jerry Douglas Band quite well. Jerry's played and recorded with damned near EVERYBODY in music.

Same thing with actors. My daughter's father-in-law's sister is actor Grace Zabriskie. Grace is not all that well-known, but she has worked with David Lynch on a number of projects and David Lynch knows EVERYBODY in Hollywood.