Sigil - Sigil is a multi-platform WYSIWYG ebook editor. It is designed to edit books in ePub format.
Pressbooks - Create books: print and ebooks
Vellum - Free beautiful hand-curated wallpapers for the iPhone
Meminto Stories - Meminto Stories makes it easy for anyone to become the author of their own book.
Papermine - Create stunning digital booklets.
calibre - Ebook manager, viewer & converter