Quark.io - Software sketchbook for node projects.
calibre - Ebook manager, viewer & converter
Kitaboo - Kitaboo is a cloud based digital publishing platform to create, publish, distribute interactive multimedia-rich & mobile-friendly digital content.
FBReader - FBReader is an e-book reader for various platforms. Features:
Zmags - Zmags provides solutions create and publish web experiences instantly.
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.