With this plugin you can add a list of links to posts having the same tag(s) of the current post.
Related articles by tag is a plugin that will display, after the post content, a list of links to posts that have the same tag. It is a great way to have the search engine index all your pages. You can tag pages as well so they can be part of the related articles. The plugin comes with a handy widget if you don't want to use the shortcode. Use the shortcode [related-articles-by-tag] where you want the related articles to appear.