I've seen Erik Naggum's name mentioned in this context before, but years ago I looked through a bunch of his contribution on comp.lang.lisp and couldn't see anything justifying this reputation. His articles rather looked quite eloquent and thought-through. Could you provide an example?
I just re-read Xah's notes and all of that rings a bell, but off of comp.lang.lisp Erik could be incredibly kind in helping other programmers. I was working my way through an early edition of _A programmer's guide to Common Lisp_ by Deborah Tatar and got absolutely stumped on the chapter on macros. Erik worked with me over email until we actually found what appeared to be a typo in the example source code and was incredibly patient with my dumb mistakes.
I've accessed that wiki.c2 for various discussions about programming before. However, I get confused with the format, specially here where it seems like a thread full of comments (no mention of usernames) there. (I like the relative minimalism and simplicity of the discourse though)