Display template name of the page you are currently on at the top of the page.

function.php

//WordPress uses a variable $template to store the template being used. Therefore, for debugging (not recommended for a live site), you can put this in your theme's functions.php:

add_action('wp_head', 'show_template');
function show_template() {
	global $template;
	print_r($template);
}

There's also a hook for changing the template that's being included for bonus points.

add_filter( 'template_include', 'bd_change_template' );
function bd_change_template( $template ) {
print_r( $template );
return $template;
}