The biggest thing I think is missing is the ability to send private messages. It appears that the way it's set up now you can only send private messages to people you're friends with. You can put a comment on their "My Page", but then everyone can see it.
I would love to see sub-forums. I think the discussion forum categories are too general and it makes reviewing the information difficult. By having some sub-forum categories (for example under Supplements have sub-forums for Protandim, CoQ10 etc...) I think ti would organize information easier, make the forums more readable and would be easier to find information.