Princeton University Press has just published GMU economist (and my friend) Bryan Caplan's book, The Myth of the Rational Voter: Why Democracies Choose Bad Policies. I haven't see the book yet, but I've read several of Bryan's articles on the subject, which are absolutely fascinating. I'm ordering my copy today.
UPDATE: Tyler Cowen writes that its "one of the two or three best books on public choice in the last twenty years." And economist Greg Mankiw of Harvard writes that it's "the best book I've read lately."