I'm not sure how it picks the songs, but it's evidently not based on tonality or musical structure the same way Pandora is. Case in point: "Ballad of the Beaconsfield Miners" by the Foo Fighters(an entirely acoustic, lyricless, guitar number) yields results such as "Little Cream Soda" by the White Stripes (hard electric start and vocals). Not quite what I was looking for.

It also doesn't include songs which iTunes doesn't recognize, which means my independently released Irish groups don't get put on playlists. I can't add songs either, if I think they go well together.

It's just not as impressive as I thought it would be, but still, cool feature.

"Brick", Ben Folds Five. "Chocolate", Snow Patrol. "The First Day Of My Life", Bright Eyes. "Crash Into Me", Dave Matthews Band. "We're Going To Be Friends", The White Stripes. "You and I Both", Jason Mraz. "Bigger Than My Body", John Mayer. "Hurt", Nine Inch Nails. "Blister In The Sun", Violent Femmes (Not really sure how this one got on there). "Pardon Me", Incubus. "Buddy Holly", Weezer. "Dashboard", Modest Mouse. "Where Is My Mind?", Pixies. "Disarm", Smashing Pumpkins. "Who Will Save Your Soul?", Jewel. "Everyday", Dave Matthews Band. "Evil", Interpol. "You Oughta Know", Alanis Morissette. "Black Hole Sun", Soundgarden. "Sex and Candy", Marcy Playground. "Wherever You Will Go", The Calling. "Do You Realize??", The Flaming Lips. "The Way", Fastball. "No Rain", Blind Melon. "Say It Ain't So," Weezer.

Great article, awesome summary.