This is simple to do on an individual-thread level, which might be helpful for a werewolf thread. Add a bookmark that points to the "go to first new post" link. You can get the link by left-clicking on
and then paste this into a bookmark, or just appened
-new to the end of a thread url.
For example, this thread is
http://forumserver.twoplustwo.com/55/about-forums/atf-chatroom-o-t-chat-1494 so a bookmark to
http://forumserver.twoplustwo.com/55/about-forums/atf-chatroom-o-t-chat-1494-new will always take you to the first unread post.