Cool company coming out of Chicago via Kapil Chaudhary called One Llama. It's an online music service similar to Pandora. However, Pandora employs a bunch of people to listen to music and categorize what they hear. There is no arguing that it has resulted in a great service.
One Llama has taken a different approach and has built software to classify music. It's not quite People vs. The Machines but it's a step in that direction. Personally, I'm fascinated by the thought that there good be little intricacies inside of a song that make me want to like it, but that I can't consciously pick out. One Llama would solve that problem for me. It would be even cooler if they could expose what those little things are. I say "would" because One Llama is still in beta so it's a little rough around the edges. Be gentle with it.
The Chicago Tribune wrote an article on One Llama today if you are interested in reading more.