Related King Pro is a WordPress plugin by Ash Durham that gives you an easy ability to display related posts on your site. The related posts are based on the tags on each post. When output, Related King Pro will get posts in order of the amount of tags that match the post your calling the plugin on.
With Related King Pro you have a few options including how many related posts will display at one time, whether not not to display images, the width and height of the image output and whether you require a placeholder (mainly for development using the placehold.it images).
Related King Pro uses a smart imaging system where it will search for your images within the post in a couple of areas. It will first look for the feature image of the post. If this is not set, it will search the content for the first image inserted. If that then doesn’t exist, it will either, depending on the placeholder setting, it will display no image code or a placeholder image in its place.
Related King Pro outputs an image (if one exists) and the title with links to the article on both surrounded by a number of containers with enough classes on them to enable you to style them to your requirements. There is bare CSS that comes with Related King Pro which allows you to style the related articles any way you need to.
Related King Pro can be used by shortcode or widget
Download: http://wordpress.org/plugins/related-king-pro/