Duke Listens!: Visit my main blog at MusicMachinery.com

Let's continue our look at music recommendation services ...

last.fm is a personalized streaming radio and music recommendation system. Last.fm builds up a listening profile for each user and based upon their listening habits can make recommendations and generate a 'radio' station (streaming audio) customized to the tastes of each listener. What makes last.fm unique among all of the music recommenders out there is that it uses an audioplayer plug-in to track what the user is playing, instead of relying on user ratings or uploaded playlists. When you enroll in last.fm, you can download and install the audioscrobbler plugin. Whenever you play a song, the plugin 'phones-home' with the details about what song you played, when you played it, and who you are. This means that last.fm can track not just what songs you have, or what artists you collect, but what music you are actually listening to. I think this is an extremely important advantage that last.fm has over other recommenders. Most people have songs in their music collection that they never listen to (for instance, my 10-year-old daughter's DisneyMania CDs are part of my music collection), a recommender that bases recommendations on what is in your collection is going to use those songs that you never listen to and give you bad recommendations. With the last.fm model, only the songs that you listen to factor into the recommendations. The more you play a song, the more weight that song is given. It is like having an automatic rating system for your music.

There are some other advantages to the last.fm model. Since it relies on an instrumented player to automatically send info back to the server, last.fm has been able to amass a very large database of music profiles. For any kind of recommendation system, the more data the better. Last.fm gives very good music recommendations (the best I've seen) with very good coverage (it is extremely rare to encounter a band that last.fm doesn't know about). Just to give you an idea of their coverage, here are some stats. In the last.fm database:

• 1,240,919 people have listened to the Beatles
• 698,795 people have listened to Weezer
• 18,324 people have listened to Dave Brubeck

There are some downsides to the last.fm model. For one thing, having to download and install a music player plugin is a technical barrier to a very large class of listeners. The non-technical users are definitely under-representated in the last.fm database. Looking at the top artist charts we find bands like Coldplay, Radiohead, Weezer and the Red Hot Chili Peppers, definitely a geek bias here, (not that that is necessarily a bad thing though...). And of course there's the whole privacy issue. Some folks just don't like the idea that their music player is sending information about their music listening habits to some remote server.

Last.fm seems to be doing a lot of things the right way. They are friendly to developers, they publish their plugin protocol, they expose their derived data via a web services interface. They even release dumps of their database under a creative commons license for use by researchers.

It will be interesting to see if last.fm can compete even as the mega-music sites like Yahoo and iTunes move into this space. I think they have a lot to offer.