If I have to comment as a user, one of the first thing that come to my mind is that we should have a navigation pane on the home page. The four tabs aren't enough.
Next, there should be drop downs to ensure better visibility.
Third, my guess is that due to too many threads under a heading, people might find it difficult to locate the threads they are interested in. SO we might introduce some more subheads with previews displayed as meta tags.
Will think more if I can
