Yeah, I've had a few of em now. Just go to the local college or high school (dressed appropriately) and ask the office if they know of any music students that would be interested in interning in a studio & leave a brochure, your card & web address & ask em to put something up on the bulletin board. You get a buncha phone calls and just by asking some basic questions and talking to a few of them, you figure out which one's are going to get the most out of it.
They get freebie lessons on how the studio works, and you don't have to clean up after yourself anymore.