I know v7n has a private SEO area. DP has a private something never went there. Also Ozzu has a (paid) member only marketplace. Only ones I know of but my forum experience is limited to only a few.
I would also like to say you guys have been great reading over one of the review my site threads had even a tenth of the comments made there been made towards any of the DP mods they would have been banned from what I have seen. Nice to a place people can speak there minds so long as it stays civil and worry about getting banned for disagreeing