Pressbooks - Create books: print and ebooks
Simple Machines Forum - Simple Machines offers free open source software such as SMF, the powerful and easy to use community forum written in PHP. Start interesting discussions on your website!
Sigil - Sigil is a multi-platform WYSIWYG ebook editor. It is designed to edit books in ePub format.
Raddle - A web-based forum where users submit links, pictures, posts, etc.
Calibre Web - Calibre Web is a web app providing a clean interface for browsing, reading and downloading eBooks...
Invision Community - Invision Community is a flexible, integrated set of apps for building communities on the web.