This plugin makes it super easy to manually select related posts. You can search and select posts that fit your criteria, all from within the write/edit post screen.
Creating a system of related posts/pages on your site will result in more page views per unique visitor, and will improve GoogleBots understanding of your content.
Display related posts automatically, using shortcodes, using widgets or use one of the available API functions to add them to your theme
This plugin supports custom post types.
See the official plugin homepage for Microkids Related Posts for more info and discussion.