I always forget AO3 technically also hosts meta, but here’s an essay on defeating “commenter’s block”, a sin I am absolutely guilty of.
It also has a link to this extremely cool script which kind of fakes inline comments for AO3, and is almost exactly how I would write a similar script if I knew how to (which I do not).
Anyway, huge shout-out to anyone out there who’s ever left a comment, no matter how brief, on a fic. You are the true MVPs.