This page has been making the rounds of the blogosphere. I like the made-up Simpsons words and many of the other links.
But one of my favorite entries not listed here is on Florence Foster Jenkins, which features a sound sample of the woman "who became famous for her complete lack of singing ability." If you have the Rhapsody music service, you can hear the entire album of this very painful warbling. (Like rain slurping down a rusty gutter, as I remembering reading somewhere.)
But one of the fun things about traversing Wikipedia and the web is finding that Jenkins' page links to a bigger page on Outsider Music, which links to this fabulous collection of 365 MP3 files of "outsider music."