A great little plugin for adding related posts to your blog has been around for a while: YARPP, Yet Another Related Posts Plugin. It’s fairly robust, for being free, but it does not natively support custom post types – a bummer.
A quick way around this is to add a simple piece of code in your functions.php file.
add_filter('wpcf_type', 'yarpp_support_func', 10, 2);
function yarpp_support_func($data, $post_type)
$data['yarpp_support'] = true;
This is a handy little solution. Simply replace ‘your-custom-post-type’ with the slug of your CPT and you’re in business. Now related posts show up just fine and you can take advantage of all the great things YARPP has to offer! Custom programming has never been easier with WordPress.