I had a recent website that needed to have a tabbed menu on certain pages that allowed navigation to other sibling pages. There are plugins that can do this and we could set the Secondary Sidebar or some other sidebar to do this on each page, but I decided to do this in the Functions.
A sample of this if found on this website: http://www.virtualworks.com/products/connectors
I created this site using Genesis and my own custom child theme based on one of their child themes.
I first created several menus that would show up (styled) as tabs on these pages. I then added the following code in the functions.php file: