Automatically adding categories and authors in custom menu?

Question

I've spent a couple of days googleling around, looking for a way to automatically add categories and authors to my custom menu as soon as they are created (the same way that pages are automatically added!), but so far no luck!

I'd really like for my client to not have to go to menu and add the category or the author to the menu manually every time a new one is created.

Any ideas?