I am unaware of any. One of the reasons this forum exists
I was a member of the Yahoo groups, but they became so difficult to work with (the website not the people) I simply walked away many years ago. Somehow my membership to both of them "expired??", and given the post count it does not seem worth rejoining.
4th edition did give this fourm a spark a while back but most discussion now is of a more general nature. Not to say 4th Ed questions are discouraged.
If you do find any please feel free to post links here (some forums stupidly don't want to advertise competitors), and if permissible let them know about us.