There is a lot of talk and movement towards OER resources for both consuming and producing. Back in 2013 we were intrigued with the potential of a wordpress plugin called Pressbooks which allowed for collaborative authoring with the ability to export as ePub, PDF, MOBI, and other formats. What we did that was unique was utilize LTI to integrate it as a tool for Moodle.
By setting up Wordpress with the LTI plugin you can create a fully integrated book publishing tool with Moodle.
Pressbooks has come a long way since 2013. It is a much smoother and refined user experience now. I am hopeful that we will get teachers and students making short stories, lessons, worksheets, and other resources that can be shared.
What I find really exciting is the inclusion of H5P within the content. We can now generate interactive books and resources. While the H5P doesn't transfer to epub or PDF yet, there seems to be acknowledgement from Pressbooks that they should work on a way to include it somehow. By linking to the web version of the book you can get all the interactions and rich content.
Here is how we implemented it with our Moodle.