Google ads are very simple to add. For example this is a custom island on my forums

Code
$time = time();

/* BODY HERE */
$body = <<<EOF

<center>

<script type="text/javascript"><!--
google_ad_client = "pub-4711273843698100";
google_ad_width = 150;
google_ad_height = 600;
google_ad_format = "120x600_as";
google_ad_type = "text";
google_ad_channel = "7536651497";
google_color_border = "f9f9f9";
google_color_bg = "F9F9F9";
google_color_link = "135060";
google_color_text = "333333";
google_color_url = "135060";
//--></script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>

</center>

EOF;

This will show four google ads wherever you choose to display the custom box. Simply name the box - 'sponsors links' or similar - you cannot use words such as 'please click these links to support our site'.