I'll supplement this main review post with some snapshot reactions to a few of Cialdini's points that prompted me to think of specific tangential issues. For now, two overarching thoughts:
First, this book provides a valuable counterpoint to works of behavioral psychology and economics that emphasize the internal biases that affect individual decision-making. Although those works sometimes address social factors and Cialdini sometimes touches on the classic behavioralist issues (loss aversion, endowment effects, etc.), Cialdini's focus on influence and compliance is still refreshing.
Second, the more practical side of Influence, especially the information that flows out of Cialdini's undercover work, raises issues akin to those of publicizing methods of picking door locks. Cialdini is handing out the keys to human consent. Cialdini's direct advice is almost entirely defensive--he tells the reader how to ward off the tools of compliance, not how to deploy them--but it is easy enough to imagine ways to gain influence. For one example, I am highly confident that the techniques Cialdini describes, carefully applied, could help professors positively influence students' evaluations of their courses--an extremely valuable skill. I leave the reader to consider the implications of that possibility.