This is sort of a quick and dirty list. I will be working on it. If you have a favorite site you think I should add, place it in the comments.
PaleoDiet
Caveman Forum
Mark's Daily Apple
Mark's Daily Apple Forum
Robb Wolf
Food Renegade
The Perfect Health Diet
Paleohacks
Beyond Vegetarianism
Agri Dynamics
Eat Wild
Slanker's Grass fed Meats
GAPS Diet
SC Diet
Dr. Gundry's New Evolution Diet
Neanderthin
Paleo Brands
Polyface Farms
Primal Mind Primal Body
Danny Roddy
The Tribe of Five
The Garden of Eating
Arthur Devany
USA Elk Meat
Caveman Strong