Readarr is a ebook (and maybe eventually magazine/audiobook) collection manager for Usenet and BitTorrent users. It can monitor multiple RSS feeds for new books from your favorite authors and will grab, sort and rename them.
Audiobookshelf is a self-hosted audiobook server for managing and playing your audiobooks.
Calibre-Web is a web app providing a clean interface for browsing, reading and downloading eBooks using an existing Calibre database.