CodeCanyon - Meganizr - Responsive CSS3 Mega Menu | 386 KB
Meganizr is a user-friendly, highly customizable, flexible and easy to integrate solution to build your custom menus. It was build with pure CSS3 which makes it simple to get started but powerful enough to create highly customized and creative mega menus configurations.
DEMO:
http://codecanyon.net/item/meganizr-responsive-css3-mega-menu/2629504