I have a [very] small vinyl label, and a few years ago, I was making an album for a band called Rebreather (OH heavy stoner stuff). We attempted to do something that I don't think has ever been done (visually)... have a translucent label, so when you held it up to light, the A & B sides would form a picture- but a different pic, depending on which side you were looking at. Well, after many failed attempts, we scratched the idea and released a not-retail-friendly "Clear Album". It was clear vinyl, no label, and a clear jacket... no writing anywhere. Not what we wanted, but it was still pretty cool.
Hah, I just googled the album, and found a site selling it for $32! (I sold out a long time ago.)