Behind the Music: Sleuths Seek Messages In Lyrical Backspin

When Jeff Milner installed software on his Web site that could play digital songs in reverse, he tested it with a snippet of Led Zeppelin's "Stairway to Heaven." The song, heard normally, refers to "a bustle in your hedgerow." Played backward, says Mr. Milner, the line sounds like: "Oh, here's to my sweet Satan."

Today, Mr. Milner's Web site plays parts of songs from the Eagles, John Lennon, Britney Spears, Eminem and others -- both normally and in reverse. Mr. Milner, a Canadian college...