The CD package for the Pat Metheny Group's Imaginary Day album (Warner Bros., 1997) was full of symbols. No explanation was given in the CD package, but it was a basic alphabet substitution code. I made this key, if you'd like to know what the album cover says.
Was I patient enough to decipher the code? Of course not. The official PMG site made available a small program that showed symbols for letters typed by the user. You may want to download the translator for yourself, though the above picture tells you everything it does.