Place this snippet of code in your functions.php file or in a plugin and then your admin bar will display the path of the template being currently used:

function display_admin_bar_template() {
   global $wp_admin_bar;
   $wp_admin_bar->add_node( array(
      'id' => 'templateMethod',
      'title' => __( 'Template: ', 'hwid' ) . str_replace( get_theme_root(), '', get_page_template() )
   ));
}
add_action( 'wp_before_admin_bar_render', 'display_admin_bar_template' );