1. Stuff: Compulsive Hoarding and the Meaning of Things, by Randy O. Frost and Gail Steketee. If you drop the normative tone, and read the case studies for "how to" tips, this is a pretty good book.
2. El Monstruo: Dread and Redemption in Mexico City, by John Ross. This book evokes vivid memories of Mexico City. At first it feels like "gonzo journalism," but it ends up supplying more factual information than the initial tone suggests. There are few cities I love more.
3. Numbers Rule: The Vexing Mathematics of Democracy, from Plato to the Present, by George G. Szpiro. A history of social choice theory, with much more detail (yet still readable) than one is used to receiving on this topic. I liked this book very much, plus it has extensive coverage of Ramon Llull, who remains a very underrated thinker. Among his numerous achievements, he understood a significant chunk of Borda and even Arrow in the thirteenth century. The first chapter of the book is here.
4. Social Security: A Fresh Look at Policy Alternatives, by Jagadeesh Gokhale. I've thumbed this one more than I have read it. The author argues that the U.S. social security system is much less solvent than is commonly thought. I could put ten more hours into this book and still it would be hard for me to judge that conclusion. Still, for the time being this appears to be the most fully realized treatment of its issues.
5. Insectopedia, by Hugh Raffles. There's one-quarter of a great book in here, provided you don't mind non-linear literary organization and welcome the notion of "hodgepodge."