Dunno if its really that simple to make, but it's simple to explain! I know an enormous amount of people who have this request, and I simply can't find it!
Its a three-column theme based off Kubric, shown as sidebar-content-sidebar. I know of people who want it (including me!), and it just hasn't been done! So if any good thememakers are out there... if you're looking for a theme, this would be an option!