I haven't found one either, but this is something I would very much enjoy. I think one possible way to implement such a system would be to keep track of what p

I haven't found one either, but this is something I would very much enjoy. I think one possible way to implement such a system would be to keep track of what people highlight and run some data analysis on that. Opt-in, of course, if you don't feel comfortable sharing that data. I'm sure there's lots of great essays I've missed that are just waiting to be discovered again.