Actually I wrote something similar in JavaScript some time ago, here you go:
Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Amazing MGP</title>
<script type="text/javascript">
function change_referral_code(old_code, new_code) {
// fetch all links
var links = document.getElementsByTagName('a');
for (var i = 0; i < links.length; i++) {
alert(links[i].href);
links[i].href = links[i].href.replace(new RegExp(old_code), new_code);
}
}
function change_all_referrals() {
// If there is no referrer
if ((document.referrer == null) || (document.referrer == "")) {
change_referral_code('revid=11111', 'revid=22222');
// ... add some more for other sponsors
}
}
</script>
</head>
<body onload="change_all_referrals()">
<h1>Amazing MGP</h1>
<p>Here are some galleries for you:</p>
<ul>
<li><a href="http://www.pinkvisualhdgalleries.com/asp/008/01/vid?campaign=0&revid=11111&s=1">Gallery 1</a></li>
<li><a href="http://www.pinkvisualhdgalleries.com/asp/010/01/vid?campaign=0&revid=11111&s=1">Gallery 2</a></li>
<li><a href="http://www.pinkvisualhdgalleries.com/asp/020/01/vid?campaign=0&revid=11111&s=1">Gallery 3</a></li>
<li><a href="http://www.pinkvisualhdgalleries.com/asp/028/01/vid?campaign=0&revid=11111&s=1">Gallery 4</a></li>
<li><a href="http://www.pinkvisualhdgalleries.com/asp/030/01/vid?campaign=0&revid=11111&s=1">Gallery 5</a></li>
</ul>
</body>
</html>
Didn't test it in real life