You should know this...

Users:

Cheb FAQ - who am I, etc.
Using jDoom - this page contains useful tips and other info (mostly model-related) from user's point of view. In short, you'll find here some info that is missing on SkyJake's official DHQ site. But you surely need to read his "Beginner's guide" and other info from the DHQ site first.
Troubleshooting - not too much info is here for now: the latest Doomsday version and latest model packs are quite stable and easy to install. Probably this section will soon die out as mammoths did.
Per-model info (includes screenshots of all monsters, authorship info, models weight in Mbytes and their polycount)

Designers:

MD2 and DED creation tricks - a "must read" for all model makers. Includes lot of links and describes common mistakes and pitfalls.
KS2 documentation for MOD developers - read this if you plan to create any add-ons or MODs!
How to properly create KSL language templates - read this, if you plan to translate KS to your language.