I found maxforums.org and that’s pretty good. There are definitely mind-bending great artists there, but they’re not as active as I would hope. Maybe these Unity forums have spoiled me! 
So I’m wondering if there is a great 3ds Max forum out there if anybody knows…?
Most of the major art forums have good advice on all 3d apps including Max, so it’s worth checking them out too. Try some of the following
http://www.threedy.com (loads of tutorials on 3dtotal.com too)
http://www.gameartisans.org
http://forums.cgsociety.org
If you want something more specific then there are decent sci-fi and military forums such as http://www.scifi-meshes.com and Military-meshes.com - 3D Military Forums