Alot of discussions/ideas about adding external links to notebooks. While the notes section under product works, it does not address the business need to providing a link on a page that is in-context to the page's content.
The new functionality release in the notebook editor could easily be extended to perform this function. Links could be added to the text box or new hyperlink box be provided.
Thank you for the request. We just shipped an update where links can be pasted into a slide, or typed into a text box. The links can then be clicked from the Notebook web page.
I will need to try it..