CSS-Class-Change.js

<script type="text/javascript" charset="utf-8">
    
var newClass = document.getElementById('classes'); // This is the class name of your dropdown menu with the new classes
var div = document.getElementById('div'); // Is the ID of the element you want to change class on.

addEvent(newClass, 'change', function() {
	div.className = newClass.value;
});
	
// Based on the lessons from Nettuts
function addEvent(obj, evt, fn) {
	evt = evt.replace('on', '');
	if( obj.attachEvent )
		obj.attachEvent('on' + evt, fn);
	else
		obj.addEventListener(evt, fn, false);
}
</script>