Groundswell: Winning in a world transformed by social technologies.

I've been working my way through Groundswell, by Charlene Li and Josh Bernoff. If you're up to speed on Web 2.0, a good part of the book will not be new to you (it's obviously targeted more at the corporate customers of Forrester Research, where the authors worked.) But the book does have real value in showing how particular businesses should make quantitative decisions around social internet participation, and also providing frameworks for calculating potential ROI. I'd say that even if you're very familiar with the social web as a firsthand user, it's worth at least skimming Groundswell before any new project to look at the frameworks they provide for assessing potential social web projects. Even if you disagree with their conclusions, it may provide a good basis for explaining or justifying your own view to other constituencies.