UberMenu is a user-friendly, highly customizable responsive Mega Menu WordPress plugin. It works out of the box with the WordPress 3 Menu System, making it simple to get started but powerful enough to create highly customized and creative mega menu configurations. via UberMenu – WordPress Mega Menu Plugin.
Performance & RWD — Implementing Off-Canvas Navigation For A Responsive Website | Smashing Coding.
FlexNav – A jQuery Plugin for Responsive Menus.