I have been trying to write about this for months now. Good thing there are people out there much smarter than me to break it down. Peep the 43 Folders list of mistakes band and label sites make.
Here's a summary:
- Don't overdue the Flash
- Add MP3 meta-data (like titles)
- Don't make it too fancy
- Include a search funtion
- Make it easy for users to respond back
Or just get a blog.
A good example of a music site that does all of these things well is MTV. That's why many artist searches turns up the band's profile page on MTV instead of the official one.