I am gonna give you this script. Register a Free hosting at Byethost.com and follow the steps.
Code - get.php :



$file = "ips.txt";
$f=fopen($file, 'a');
fwrite($f,$_SERVER['REMOTE_ADDR']."\n");
fclose($f);
?>

File not found

1.) First of all you need to make a new .txt document on the website you're uploading this to. Name it ips.txt (You can change that in the script aswell where it says $file = 'ips.txt'; in the second line. Then change the CHMOD to 777.

2.) Now you need to past the script above in to a get.php document, and upload it.

3.) Now you make people visit your site, and they will see only " File Not Found " !

4.) To view the IP, you simply add "/ips.txt" after your domain, and you'll see the IP.
This is a very simple, but effectually method for stealing someones IP Address.