<div id="whatever">
<a href="/path" rel="7">peace</a>
<a href="/path" rel="3">unity</a>
<a href="/path" rel="10">love</a>
<a href="/path" rel="5">having fun</a>
</div>
and then:
$.fn.tagcloud.defaults = {
size: {start: 14, end: 18, unit: 'pt'},
color: {start: '#cde', end: '#f52'}
};
$(function () {
$('#whatever a').tagcloud();
});