D&D Compendium now has a Discord server!
/r/OutOfTheAbyss
Out of the Abyss DMs Discord Server
Out of the Abyss DMs Facebook Group
Elven Tower Guide
PowerScoreRPG Guide
Sly Flourish Guide
A DM's Thoughts on OoTA
Some suggestions from a Reddit user
EN WORLD Out of the Abyss Resource Collection
OoTA Random Encounter RNG
Out of the Abyss Walkthrough Poster