The Cathedral and the Bazaar
I have read this book of essays a couple of times, the last time as a refresher for a project I am currently working on. I like the book, its approachable and well informed and covers the history and philosopy of Open Source well.
However it does suffer from being a collection of essays, and not a well structured book, and some of the analysis is a little superficial. For a thorough treatment of the subject I recommend
Its worth noting though that you don’t need to buy the book, its available online here.