BNE Flyouts is a WordPress plugin that adds off-canvas hidden sidebars with any custom content that will push in on every page of your site from a trigger or action. Any content you put in the Flyout will not display until the user triggers a floating button, floating image or linked from any element from your page content.

Demo: http://codecanyon.net/item/flyouts-off-canvas-custom-content-for-wordpress/7837448