A long time ago I posted an item called Useless Trivia in which, aside from the Girl from Ipanema's legal problems, I mentioned my taste for Nu Samba/Bossa Nova and my search of the web for information about it. One of the techniques I used was to go to my blogger profile, click on the musicians I had listed, and then go to each of the other blogger's profiles and see who else they had on their list. Needless to say, a long and tedious process.
Recently, I found an interesting little site called Music Map. It is a project that is attempting to aggregate musical tastes from a large number of people and then visually map the connections between muscians people like. It is also doing this with books and movies. In testing it the names I entered didn't always appear. Perhaps the database driving it is still small, or more likely I have an eccentric taste in music. Regardless, it sure beats the brute force 'blogger profile' technique I had used.
The main page of the site is located at Gnod.
As an aside, Kartoo is a search engine that present a similar mapped output.