Hugo Award winning author Lawrence Watt-Evans (aka lwe, his wiki page here. Check out that bibliography.) previously posted the first draft of one of his Ethshar books, a chapter at a time, over on his website. It was run on the donation model, and once the book was finished, he revised and released as a tpb.
Now, he's doing it again, this time with a science fiction novel called Realms of Light. The first chapter is here. If you're interested in this sort of thing, it's a chance to read an established pro's first draft.