Sigil - Sigil is a multi-platform WYSIWYG ebook editor. It is designed to edit books in ePub format.
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Vellum - Free beautiful hand-curated wallpapers for the iPhone
Unsplash Wallpaper - Gorgeous wallpapers on your Mac
Pressbooks - Create books: print and ebooks
Splashy - Breathtaking, auto changing wallpaper app for macOS, Windows, Linux, iOS & Android