I feel like this is the third one of the November thread!
That said I will say again, working on http://leafle.org my app (mostly for me) to find new books to read that I wouldn’t have thought of (mostly recently Cosmicomics) based on a deeper understanding of what I like in books than people who read X also read Y, that I can actually borrow right away from my local library. Works on ~6,500 public libraries around the world.
Fun project to play with reverse engineering using LLMs, and jev and things like that.