WP Related Items plugin offers different types of similar contents for your users. For example some related products can be displayed to your posts.
Supercharge your custom post type archives by letting visitors filter posts by their terms/categories. This plugin handles the whole thing for you!
Add new statuses (created by user interface or from register_post_status() function) to post, page and custom-post.
Portico makes defining and administering custom post-types EASY. Define your post-type in a class, and an admin interface will be created for you.