Turn a string, list, or array of post IDs and/or slugs into a list of links to those posts.
The plugin provides a widget called "Linkify Posts" as well as a template tag,
c2c_linkify_posts(), which allow you to easily specify posts to list and how to list them. Posts are specified by either ID or slug. See other parts of the documentation for example usage and capabilities.
Particularly handy when used in conjunction with the post custom field feature of WordPress. You could define a custom field for "Related Posts" or "Additional Products" and manually list out post IDs, then utilize the function provided by this plugin to display links to those posts in a custom manner.