Well, a number of things but I thought I'd post them up as they occur.
Changes completed:
10/09/08 - Last post subject on Index page = can be quite useful.
Upcoming changes:
Quick replies - Allows you to reply on the fly without having to click Reply all the time.
User last page in profile - Displays user last page (forum location) in their profile.
Topic in "Who is online" - Displays a topic name which is looked through by the user.
New post count on index - Displays the number of posts next to the "New posts" link on the board index.