When viewing a thread it will tell you so-and-so replied, with replied being a link back to whatever comment they've replied to. Would it be possible to expand this a little, something like "#58, Chris Roberts replied to John Smith (57)" with #58 being this message number in the current thread and (57) being the number of the message I've replied to? This would make back-and-forth a little easier to track without having to go to a full threaded view, something I personally don't care for on web forums.