I'd like to suggest a "Save Thread to Favorites" feature. This feature would allow me to mark threads that I consider to have a lot of value, and my list of favorite threads would appear on my profile page. When a user checks out my profile, they can see the threads that I think are important or special in some way. This feature could save a new user a tremendous amount of time digging around the forum for really good threads. After all, if that new user likes my posts, then it's highly likely that the threads I think are really good will appeal to that new user as well.
It's a simple feature, but I think it's got the potential to be a great one.