I have signed up at The Storygraph Beta, which recommends books. Nowadays, it's strange nowadays to find a recommendation system that isn't part of some online merchant. Anyhow, most folks on there like fiction (which makes sense, since the service has "Story" right in the name), but I mostly like nonfiction so it remains to see whether I like any of its recommendations. But there's hope. I told it about a bunch of books I've read and let it recommend some more.