Free as in Freedom, Sam Williams' biography of Richard Stallman, is available for free as in money on the O'Reilly site and the author's own Faifzilla.org. It's also available for money.
Williams had trouble finding a publisher willing to release the book under the GNU Free Documentation License, he said in an interview with Raven Matrix. "Publishing a biography of RMS under an overly restrictive copyright would make me look clueless," said Williams, who hopes to see some interesting reuse of his work.
He said that interviewing Stallman for the book was a challenge:
"[T]here are few moments, if any, when you capture Richard in 'off' mode. Even when you try to make a joke about something technology-related, you go in knowing that the joke will be instantly critiqued on its logical merits. ... Hanging out with Richard is a lot like moving from the kid's table to the adult table. You can't bluff your way through an interview."
Theological question: Is it wrong to hope for a version of this book in Microsost Reader format?