While the theme for this forum does not have a link to display unread posts - those topics with new posts that you have yet to read - this is a basic feature in phpBB. I use this for several forums I follow, and some might want to use this link here as well. Click this to see the topics where you have not read posts, or marked them as read:

search.php?search_id=unreadposts

Hope some find this useful.