I've released a book of poetry here on Mobileread under a creative commons license. It can be found here:
Epub:
https://www.mobileread.com/forums/showthread.php?t=41879
Mobi:
https://www.mobileread.com/forums/showthread.php?t=41875
PDF:
https://www.mobileread.com/forums/showthread.php?t=41880
I also plan on releasing my book on the ethics of intellectual property (whenever I get THAT done) under a creative commons licence. I believe that knowledge should be freely available to all who seek it. If what I say is true, then how can I claim it as my own property? If it is false, then why would I want to? I don't derive a livelihood from writing other than from my work as a freelance journalist for a community newspaper, for which I am paid up front. I think it is possible to do so if you promote yourself properly. Cory Doctorow manages, for example. I also came across a 'Choose your own adventure' book for grown ups that was released under a creative commons license. To show my support, I purchased the nicely formatted paper edition.