You might find this a bit dry!
It’s written for ‘marketers’ rather than musicians, but I’d suggest you check it out.
It’s a report on the state of Social Media in 2011 and how brands and marketers are using it.
I found the facts about what tools people are using to help them deal with social media management as well as the things that they feel they can outsource interesting.
You might find something that helps you with your music marketing!