Mine

<?
// This function check the port status and return true (online) or false (offline)
function is_online($server='localhost',$port=80,$timeout=2) {
    $fp = @fsockopen($server, $port, &$errno, &$errstr, $timeout);

    if (!$fp)
        echo "<strong><font color=\"red\">Offline</font></strong>";
        mail(BLABLABLA)
	else
    {
        fclose($fp);
		echo "<strong><font color=\"lime\">Online</font></strong>";
    }
}
?>

@@HTTP <?php is_online('127.0.0.1',80) ?>