There's http://news.ycombinator.com/newest http://news.ycombinator.com/newest and http://news.ycombinator.com/newcomments http://news.ycombinator.com/newcomment

There's http://news.ycombinator.com/newest http://news.ycombinator.com/newest and http://news.ycombinator.com/newcomments http://news.ycombinator.com/newcomments for new submissions and comments, respectively.