add_action( 'wp_head', 'show_me_the_template' );
function show_me_the_template() {
	global $template, $current_user, $wp_admin_bar;
	
	get_currentuserinfo();
        /* If you have more than one user deny. Be sure to use your user ID! */
	if ( !is_user_logged_in() && $current_user->ID != '1' ) 
		return;
	if ( is_admin_bar_showing() )
		$wp_admin_bar->add_menu( array(
			'parent' => false,
			'id' => 'template',
			'title' => $template,
			'href' => '#'
		));
	else
		print_r( $template );
}

add_action( 'wp_head', 'show_me_the_template_butthead_hehe' );
function show_me_the_template_butthead_hehe() {
	global $template, $current_user, $wp_admin_bar;
	
	get_currentuserinfo();
        /* If you have more than one user deny. Be sure to use your user ID! */
	if ( !is_user_logged_in() && $current_user->ID != '1' ) 
		return;
	if ( is_admin_bar_showing() )
		$wp_admin_bar->add_menu( array(
			'parent' => false,
			'id' => 'template',
			'title' => $template,
			'href' => '#'
		));
	else
		print_r( $template );
}

This will show you what template you are currently viewing (index.php, page.php)

Template Finder for Wordpress

wordpress

PHP