Required commercial (paid) software: AllWebMenus PRO (v5.3.884+)
This plugin offers an integration for the AllWebMenus PRO software into a WordPress blog. As such, AllWebMenus PRO (v5.3.884 and above) is required to be installed in your machine.
The AllWebMenus WordPress Menu Plugin offers the ability to add an item at the end of your menu that contains a submenu that displays the most relevant posts (or pages) of the post you are currently viewing (the item will appear only when you are viewing a single post).
This feature is build on Yet Another Related Posts Plugin by mitcho (Michael Yoshitaka Erlewine). Visit the YARPP plugin's site.