display a node in the sidebar region of another node I'm a huge fan of annotating content in the margins of my real paper books. 

In drupal 7, I want to be able to annotate a book page content type by showing a child of that page in the space beside the main page. 

Has anyone done anything like this before in Drupal? Any links?

You might describe it like putting comments next to the page but I would prefer to use child pages if at all possible. 

Thanks for any suggestions or help.
You could in your template file just render the comment section in your sidebar.