D12 Critical Hit & Fumble Tables for your amusement | Nerd-O-Mancer of Dork
d10 Insanity Effects : r/d100
D&D: Stress and trauma as an alternative to Madness (unofficial 5e homebrew supplement) by flipwix
Revised OotA Indefinite Madness : r/OutoftheAbyss
The Remedy - A Cruel Adventure delving inside the Depravity and Madness of an Eldritch Curse [Steinhardt's Guide to the Eldritch Hunt] : r/DungeonsAndDragons