WordPress find current post type

/**
 * Work out the current post type
 * - based on WP function or current taxonomy
 * @author Adam Onishi (aonishi@wearearchitect.com)
 */
function dig_current_post_type() {
	global $post;

	if( ! is_tag() ) {
		$type_name = get_post_type();

		if( ! $type_name ) {
			$taxonomy = get_query_var( 'taxonomy' );
			$type_name = substr_replace($taxonomy, '', -9);
		}

		return $type_name;
	}
}