Yep! It's called bandwebsite, actually. Just do a search for it, I forget where it is. It needs php and mysql, and still has some bugs.

I'll be trying out PostNuke, myself, once I get php and mysql working on my host. Mostly because I want a bit more of a community site than just a band site.

The only thing is, mysql database access sometimes isn't cheap, depending on your host. I really think it's worth it, though, because it's SOOO easy to update the information on a site if you use php and mysql.