This is a theme I developed in response to my need for a system with a vertical menu in the sidebar. I find more and more that I need such a menu when the customer's site has 7 or more menu links. The horizontal menu systems are more limited in the number of links allowed.
I based this theme on the wonderfully flexible themes devised by Andreas (don't know his last name or country of origin).
Quite simple: Extract ZIP archive to your GetSimple's /theme directory and enable it from administration panel.