1)Video content never fails to resonate with users, it would be great for artists to embed their existing online video content somewhere on your site.
2) Do any of the artists have their own groups on Ning? Can you create a loop somehow?
3)Do the artists have flickr groups? Are they on tour, can you integrate their Dopplr profiles if they have them?
4)Geographical info mashup? Where is the music coming from? Where do the artists live? Can you figure out how to provide information regarding gigs?
5)Take the blog more seriously. Maybe don't hide it? Blog more often, mention music related links and stuff that may not directly concern the site. Maybe you should think of the blog as the marketing? (feedback loop again)
I could continue but I'm not sure if I'm on the right track here. I look at everything with a marketing/social engineering prospective, I don't write code. Let me know HackerNewsCommunity and I'll give it some more thought.