I've blogged about/pushed Pandora before, but I haven't mentioned Last.fm. This is odd, since I use Last.fm all the time, and rarely use Pandora. I'm just always reticent to recommend anything that requires any installation, as Last.fm does, no matter how unimaginably valuable I think it is.
Here's the breakdown:
With Pandora, you voluntarily submit artists/tracks you like or dislike. Pandora consults a bunch of data assembled by a staff of experts. It then recommends (and plays) music that the experts have determined to have similar properties as the songs you like.
Last.fm, on the other hand, has no experts, the expertise comes from the crowd. Last.fm's "audioscrobbler" determines what you like by monitoring your behavior, by continually monitoring what you actually listen to on your music player. It takes this data and blindly compares you to others who listen to the same tracks to determine some recommendations (and can also function as a personalized radio station).
I think the reason I prefer Last.fm is because "statistics will triumph over design, no matter how knowledgeable a group of musicologists you assemble." But there are definitely arguments in Pandora's favor. Steve Krause provides a pretty detailed analysis
A final thought: What Last.fm and Pandora do is hard, and the people who built these services deserve a lot of credit. Given the ambitious scope, it's easy to find examples where each of the services comes up short. However, it's worth considering what the yardstick should be. Should we expect spot-on recommendations like a pro bowler expects a strike every time? Or is this more like the baseball batter, who is happy to get a hit one in three times? Whatever the metaphor, the fact that these services do enough right to retain a substantial number of users is good news, because the features and quality will only get better.
The Long Tail* provides another breakdown of where they fit conceptually, along with Amazon and eBay ratings.
*The Long Tail is named for an interesting cultural theory, basically that as means of production improve, we naturally shift from generalized products to specialized ones... we move from newspapers to magazines. It might predict that the feasibility of personalizable radio stations sharply undermines the need for commercial radio stations.
This is a test: