Related Links can choose the most related pages from your site and show them in a gadget. You can embed this gadget in your page to help your users reach other pages easily and thus increase page views.
Related Links also suggests searches that users can run within your site to find even more related pages.
But unfortunately only invited users can use Google related Links.However you send them an Email to stating your Gmail address, website domains and approximate page views per day to get an invitation.
Update: Google related Links is now closed and can’t be used.
You can also use other option for adding related post,for example YARRP, LinkWithin etc.