I'm sorry if this has been mentioned already, I haven't read all the other posts.
BUG: When I have read a topic and return to the forum later on, the topic is marked as unread even though there are no new posts. (I reckon the paper with a green plus sign on means unread).
SUGGESTION: On the main forum page there are no signs at all suggesting if the different sub-forums contain new posts or not. It would be great if there were... ;)