Way back in the day I worked on a website called MyLaunch which later changed its name to Launch before being bought by Yahoo where it now lives
One of the features it boasted was collaborative filtering using what was then called Firefly technology. The problem was that users had to go in and rate a bunch of songs and artists before you would get any meaningful results.
It would have been nice if there were some way for the site to simply listen in on what you were listening to and make recommendations based on your actual habits. That’s what Last.FM does.
There are two components to Last.FM, a plug-in that sends information to the Last.FM web services about the music you are listening to. This requires a plug-in to your favorite audio program. I installed the iTunes plugin.
The second component is a player that delivers a customized radio station with selections based on your tastes. I haven’t used this but Jon Galloway writes about a C# player that is a worthwhile replacement for the lame player offered by Last.FM. Jon recently open sourced the codebase started by another developer, Eric Willis, with his permission.
Give it a twirl. You can see what amazing taste in music I have by checking out my Last.FM profile page.