Outside of self-hosted solutions, there’s JustWatch, which allows you to create an account, add movies and TV shows, and then you can rate them and get recommendations for it. It’s not FOSS, and you do have to create an account, but it does let you have a universal watch list for all services you own, and then see what people are watching and get recommendations.
Getting onto MyAnonaMouse was the best thing for me for audiobooks. They have open applications once every week I think, and they have most of the audiobooks I ever need, and many that I didn’t know I needed.