Against Intellectual Monopoly: http://www.micheleboldrin.com/research/aim.html (appropriately, the authors offer it online for free)
Interesting challenge to what is commonly termed intellectual property (trademarks, patents, etc.); why we don't necessarily need it and why it probably is very bad and counterproductive.

You and the State: http://www.amazon.com/You-State-Introduction-Political-Philosophy/dp/0742548449
Good introduction to political philosophy from an anarcho-capitalist perspective.