During registration have a selection option that places the user into a permanent group (unless admin changed). Personally, I want affiliate, publisher, and other. And I want to display it under their username.
Allow a user to have control over his referrals. Example referrer could limit what forums their referral can see when logged in even if these are publicly viewable. (Yes, this is actually an important feature so that the referrer can 'focus' the referral)
Blogs. I've tried to look up the plugins for blogs and its not clear quite how they work. I want each and every user to be able to start their own blog, not just create blog posts under a category. I really want a url structure like www.example.com/MyBlog or www.example.com/blog/MyBlog to have the user's blog posts like a normal blog and with the ability for the user to name his blog. There needs to be different blog categories. But then, post categories should be global so www.example.com/category-base/post-about-category-base shows all posts by everyone in that category. It would be amazing if each user could customize certain things about their own blog page. Something similar to patheos.com/blogs/graceismessy would still be fine (no affiliation, literally grabbed from the front page).
The referrer would have 'moderating' privileges over their referral's blogs in order to help remove hateful / spam comments.
For the blog posts, comments should be able to come from forum accounts or public (like facebook).
Groups -- in addition to the initial group categorizing sorting on signup, there also need to be groups that members can join. For instance, California Pay-Per-Click Affiliates.
I think there is an addon that allows the forum to sell access to a hidden forum?