I downloaded iTunes 8 over the weekend, with its much publicized Genius feature that creates "perfect" playlists based on a single song and suggests similar songs from the iTunes Store.
According to Apple propaganda "Genius playlists help you discover songs in your library you never knew you had". If you can discover songs in your library that you never knew you had, you have too many songs in your library!
I found Genius playlists more painful than perfect. It chokes on songs by artists that aren't available on iTunes (like the Beatles) which reminded me of this John Lennon spoof from National Lampoon's Radio Dinner, "Magical Misery Tour" (NSFW)
Every word of this track is taken from John Lennon's 1970 interviews with Rolling Stone, so its even funnier for anyone who's read the interviews.