Mockupea - Mockupea is an online tool for creating 3d book mockups with a lot of features.
Papermine - Create stunning digital booklets.
Stackoverflow '90s - Bring back '90s to Stackoverflow with this extension
Pressbooks - Create books: print and ebooks
Box Shadow Generator - Generating CSS3 multilayer box-shadow has never been easier.
boook.link - boook.link is a web-based tool for creating one single link / landing page for a book, so your readers can choose from which store to buy the book.