Coulton Creations

Jonathan Coulton's website is a treasure trove of geekalicious music. My favorites so far include Mandelbrot Set, The Future Soon, Betty and Me, Chiron Beta Prime (it's a Christmas song!), and Re Your Brains. Also, you must check out his hilarious cover of Baby Got Back. All the music is free, though the artist requests donations. You can also find most of Coulton's stuff on iTunes, which makes the donation process a little easier if you don't do PayPal.