The wp_after_admin_bar_render action allows developers to modify the $wp_admin_bar object after it is used to render the Toolbar to the screen (if enabled in user preferences).
This action is triggered right before the last action - shutdown action, when PHP execution is about to end.
function my_custom_admin_bar() {
global $wp_admin_bar;
//Do stuff
}
add_action( 'wp_after_admin_bar_render', 'my_custom_admin_bar' );