I always found these discussion boards hard to follow because of the way they're laid out. I'm not sure if I'm allowed to promote this here but I made an area on Reddit to discuss Meg's books. The subreddit is called /r/MegCabot.
As of right now, no one really discusses anything because we don't have a community. I'm hoping some of you will try it out. I really want to be able to discuss Mediator 7 when it comes out.
I'm also looking for people to help me moderate it. PM me on reddit if you're interested.
Another thing I would like to discuss is the Meg Cabot wikia. I've noticed the people that are controlling it right now do not actively update it. I'm trying to get some people to help me fix this. I know it's never going to be as spectacular as the Harry Potter wikia, but I would like it to at least have more information than it does now.