Yesterdaynight I installed the clipper.module on the Remix Reading developers site. The clipper.module allows you to add and relate content. In the back it uses the drupal taxonomy to generate the relations.
About the author: Bèr Kessels is an experienced webdeveloper with a great passion for technology and Open Source. A golden combination to implement that technology in a good and efficient way. Follow @berkes on Twitter. Or read more about Bèr.