"Free as in freedom" is a great book telling the story of Richard Stallman and the early days of the free software movement. Although quite dated by now it's still informative and insightful. Being based on interviews, talks and articles in the era of the early Internet it shows a few different perspectives on the issues of copyright, software licensing and also the private life and works of Richard Stallman and other notable people that worked with him. My only gripe with the book is that the author doesn't always fully understand the technical aspects of software and copyright he's writing about as he's clearly an outsider to the topic (this was largely corrected by Stallman himself in the 2.0 version, but he also modified the book in other ways giving explanations, comments etc). The book is strangely quite harsh and also slanderous at times, but overall it's a solid piece of historical work.