ModTree MODX Revo component
You can link resources of your site with each other and show them on a page as a tree.
A book has written by an author and published by a publishing company. The author has written other books. The company has published many books and cooperates with many authors. The book can be illustrated by a painter. The painter works with other authors and other companies.
The whole hierarchy of related objects can be displayed on your page easily.
Just make links between resources. See result on examples