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.
WP Related Items plugin offers different types of similar contents for your users. For example some related products can be displayed to your posts.
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.