cat-v.org/ by Rob Pike, co-creator of Go, looong time Unixer, and some kind of leader of a 9p resurrection cult. That one's spicy. E.g.: harmful.cat-v.org/, Ciro's version: good and evil.
Gwern Branwen's website.
One thing that annoys Ciro Santilli about that website are the footnote overload. Ciro likes linear things.