I'm not sure there's sufficient demand for another forum. Probably as MoI gets a larger user base over the next couple of years the forum here could have some categories.
I run a Cinema 4D forum. Easy enough to set up a forum but you've got to be committed to manage / run it every day or get people to assist you. I've seen people start up Cinema 4D forums expecting them to take off and give up 3 months later after finding it hard going getting anyone to post.
It would be good if Michael could introduce Categories in to the forum. However, I guess that would mean changing the forum software, which could be a big job.
