I just finished skimming a totally boring book: Social Networks and the Semantic Web, by Peter Mika. It might be great if you're into academic language and maybe have a PhD. I don't, so it was not riveting.
The one concept that was sort of new to me is the idea that you can be a unique bridge between various spheres of interest. You might be the only person on this planet that could make an important connection between someone you know and someone they need to know! So the area of social media does have payoffs. Some are financial but the most important ones are relational.