I've seen a couple posts allude to this, but...
Improving discoverability and navigation of the forum would be a godsend.
As a newer member, I'd love to be able to browse through older discussion posts which are not company-specific. I'm sure there are some great intellectual conversations hiding in the forum which contain more general investing/other knowledge and are not getting the eyeballs they deserve.
There are loads of things that can be done here but a "simple" start would be a split of forum content into company-specific and "General discussion topics" with the ability to sort general discussion topics by popularity.