Writer Cory Doctorow has an interesting little scam going:

When my first novel, Down and Out in the Magic Kingdom, was published by Tor Books in January 2003, I also put the entire electronic text of the novel on the Internet under a Creative Commons License that encouraged my readers to copy it far and wide. Within a day, there were 30,000 downloads from my site (and those downloaders were in turn free to make more copies). Three years and six printings later, more than 700,000 copies of the book have been downloaded from my site. The book's been translated into more languages than I can keep track of, key concepts from it have been adopted for software projects and there are two competing fan audio adaptations online.

Yet somehow, Cory says that this has earned him some money. Read more about how this worked out for him at Forbes.com.