Mark all as read

Now that we finally have working "new", I think the next step to that particular feature is mark all as read. I am not going to read every post in every forum, but seeing almost everything marked as new all of the time means I might miss some posts that would stand out as new otherwise. I don't know how often every single topic might have something new, but I won't know unless I have a quick option to clear them all. I imagine some topics will almost always have something new because they're very busy, but others should fall away so I would notice the real new ones.