Maybe make another way of browsing on-going topics/articles other than by searching. I tried a few keywords and couldn't get any results so I gave up. If I had been able to click through a menu or what not to find "most active" or by category I would have spent more time and had the opportunity to see your product "in action".
Yes, I definitely intend do give some sort of "Browse" navigation in future - maybe with a tag cloud? It's currently not on the site because I have not much content right now as I just launched it a few days ago. If I had top categories they will all be empty :) I will put them on once I have some sizable content.