I think it would be great if the headlines of the topics would be edited for a better overview. Titles like "My Suggestion" or "New Story Proposal" don't say a thing. For example, I know that I read the idea for an XSP-Story that was supposed to play on a starship, and I wanted to add my thoughts, but I can't find it and have to read through all threads (which are not that much at the moment, but these boards will grow when XSP becomes more popular), which is very time consuming and frustrating because of that.
I come from a Fanfiction-Site and also have a decade of experience writing on message boards, and either the authors of threads with non-specific titles are asked to find a meaningful title, or the admins/operators give a title. There would be two sides which benefit from clear titles: The author who started the thread would attract more readers and more answers, and the users would find the topic they were looking for on first sight. So it's a win-win.
I give you an example. Which one would be the first message board to read?
Sci-Fi-Theme: "Lust in Space" - A sexy Space Odysseyor
My Suggestion 
EDIT: Yeah, I know, I could use the Search, but it gets really annoying if you have to search for every bit because the starter of a topic couldn't make up a proper title.

2nd EDIT: I tried the Search function, but I couldn't find the post I was looking for. Neither can't I remember special words used in the reply, nor can I find it in the "Story Proposal" Category. Guess I lost it. That's a little disappointing.
3rd EDIT: I thought it over, and I want to say that I withdraw my suggestion of moving similar threads together. Since the category "Story Proposal" seems to be more like a story archive and less like a discussion/question-board, it makes more sense to keep the proposals of different people in different topics, just as if somebody would post a story on a fanfic-site, and other users can comment or write a review.