5. WP Simple Related Posts – Related Post Plugins For WordPress
I often prefer related post plugins that gather links from categories and tags. This cuts down on the required processing power since the plugin doesn’t need to scan your content or headlines for keywords.
With WP Simple Related Posts, you’ll get a plugin that looks solely at post tags and categories. These differ for each post, but the plugin aims to automate the process by randomizing the related links for each page.
And since this plugin is totally free, the developer released a free add-on template on GitHub. You can use this to append features onto the plugin for even greater customization.
credit : digitalcube