Extend Wordpress Admin Bar with any kind of content you like - not just links.

my-html-admin-bar.php

<?php

$getHtml = function($id) {	
?>
<div><a>
Some custom HTML
</a></div>
<?php		
};

$myPlugin = function($id, $getHtml) {
	add_action('wp_before_admin_bar_render', function() {
		ob_start();
		add_action('wp_after_admin_bar_render', function() {
			echo apply_filters('wp_buffered_admin_bar_render', ob_get_clean());
		});
	});
	add_action('admin_bar_init', function() use($id, $getHtml) {
		global $wp_admin_bar; /* @var WP_Admin_Bar */		
		$wp_admin_bar->add_menu(array('id' => $id, 'title' => $id));
		add_action('wp_buffered_admin_bar_render', function($buffer) use ($id, $getHtml) {
			if (is_callable($getHtml)) {
				ob_start(); $html = $getHtml($id); $html .= ob_get_clean();
			} else {
				$html = $getHtml;
			}
			return str_replace("<a href=\"\">{$id}</a>", $html, $buffer);
		});	
	});
};

$myPlugin('__0', $getHtml);