A huge feature of any music or band website is simple contact management. You want to keep track of fans, venues, promoters, media people. The reason of course because this creates a nice way to look people up later after you meet them.
For fans, SimpleNews module works great. But it doesn't let you do targeted email campaigns, say for only fans in New York. And it can't distinguish a fan from media contact.
CiviCRM is a full blown contact management solution but is somewhat overkill and hard to use.
A brand new module which has been released could provide a solution for this - Views Mail. It was just released so it's probably pretty unstable at the moment. Definitely something to keep an eye on though.
But it looks promising - you could create a CCK node with any contact information you want for a person, and then use Views to sort and filter users by any field. Then with views mail you could send a targeted mass email to this group of people.