Cory Doctorow has written For the Win, a novel based around gold farming of all things, and released it under a Creative Commons Licence:

It’s financially sensible in that all of this stuff just amounts to publicity, and the more publicity there is the greater the likelihood that the book while rise to the attention of a potential customer. Obscurity, not piracy, is the biggest problem writers face. In the 21st century, if you are not making art with the intention of it being copied, you are not making contemporary art.