This is super niche, but a service that takes a video upload (or youtube link) of a professional pool/billiards match and generates overhead shot diagrams for every shot of the match. Why do I want this? Diagramming shots is the most tedious part of making a book where you analyze shots from pro matches -- this has been done by hand before and sells for ~$50 -- https://www.amazon.com/Capelle-9-Ball-Archer-vs-Reyes/dp/096... . I've played with this a bit, taking photos of a table, doing transforms to get an overhead layout (with OpenCV perspective transforms and Hough detection), but it's never come out quite right. I also want motion tracking of balls so you can generate arrows for where the balls went, but honestly, just the static "balls at rest" diagrams would be worth it.