"Brad, this is timely, because I just finally started writing my first book, but I am using a very cool open source platform and loving it. It comes with a built in publishing desktop tool that uses Markdown for writing, has publishing in all formats built in and it makes complete sense to me so far. The site allows you to publish and see in their library, but you can take the books anywhere you want. Since this is my first book, I'd like to see what experienced authors think of it nad what it's missing. So far for me, it's brilliant and it's free: https://www.gitbook.io/" - Brad Nickel