Charles Sheehan-Miles, who wrote "Republic: A Novel of America's Future", explains why he's giving away his ebook in any way, shape or form you want it:
No more sample chapters, partial books that end in the middle, none of that. You can download and read the complete book. Share it with your friends, email it, do anything you want with it except sell it.
Here's why: the biggest challenge most authors face isn't online piracy. It's not people out there diabolically copying their works and distributing them for free. In fact most authors (including yours truly) suffer from a different problem entirely -- no one has ever heard of them. After all, literally hundreds of thousands of new titles come out every year, and only a few hundred writers in the entire United States (if that many) actually live off their books full time. So, by giving away the book, I hope more people actually read it.
Tim O'Reilly was the first to say that the enemy of authors isn't piracy, it's obscurity. For the vast majority of authors, being read is actually reward enough. How to turn that recognition into a living is a whole other process, and not necessarily one that depends on the traditional book industry to deliver. Good thing, too, since it so rarely does.