<SCRIPT LANGUAGE="Javascript">
<!--

function banner() {
};

banner = new banner();
number = 0;

// bannerlar
banner[number++] = "<a href=www.link1.com><img src=banner1.jpg></a>"
banner[number++] = "<a href=www.link2.com><img src=banner2.jpg></a>"
banner[number++] = "<a href=www.link3.com><img src=banner3.jpg></a>"
banner[number++] = "<a href=www.link4.com><img src=banner4.jpg></a>"

increment = Math.floor(Math.random() * number);

document.write(banner[increment]);

//-->
</SCRIPT>