php script:
<?
//"ip.php" example- display user IP address on any page
Header("content-type: application/x-javascript");
$serverIP=$_SERVER['REMOTE_ADDR'];
echo "document.write(\"Your IP address is: <b>" . $serverIP . "</b>\")";
?>
javascript:
<html>
<body>
<script type="text/javascript" src="ip.php"></script>
</body>
</html>