Thinking about it a little further with the watermarking of MP3 files. Actually Apple has already started doing some sort of watermarking with their iTunes Plus files. I remember reading about that at some point where a user figured out that there is additional information in the file tagged in it throughout the file that determines what account bought the file.

It would be great if Apple could do this via CD like they seem to be doing with DVD's.

Jody Whitesides
A Funky Audio Lap Dance For Your Ears!