also is there a way to signal on a thread if there has been any new comments since your last view? Perhaps a "last comment by ____" so I don't have to guess if someone's replied to the thread or perhaps less intrusive a little flag that notifies you of this.

Looking at hackernews they don't have this though so I don't know if that would overly clutter the UI. Maybe once you get to that level of traffic there's always a new comment...