I was looking through an audio advisor catalog just a little while ago, and came across this one:

"The Irrational, But Efficacious! test [and burn-in] CD...the main tool is a five-minute glide tone, that when played through your system at moderately low volume, will improve its sound....[the] tone helps demagnetize residual fields that build up in your components over time."

Who knew? :p