Leanpub is another way to publish books. From their website:

Leanpub is a powerful platform for serious authors. This platform is the combination of two things: a publishing workflow and a storefront. Leanpub is more than the sum of its parts, however – by combining a simple, elegant writing and publishing workflow with a store focused on selling in-progress ebooks, it’s something different. Leanpub is a magical typewriter for authors: just write in plain text, and to publish your ebook, just click a button.