As you know if you read this blog daily, marketer extraordinaire Seth Godin (who also has one of the most widely read blogs on the Internet - I read it every day) has written one of the most influential books in recent memory called Tribes: We Need You to Lead Us.
A tribe consists of members who are passionate about something, with their leader being the most passionate. In the case of music, the artist is the leader of the tribe and the tribe consists of the most passionate fans (sometimes called "superfans" or "superfriends").
The gist of the book for a musician is that in order to be successful, you have to develop your tribe and communicate with it regularly. I'll have a lot more on this in my upcoming book "Music 3.0 - A Survival Guide for the New Music Industry", which I'll discuss periodically in the coming posts.
Here's a brief interview with Seth discussing tribes, among other things.