$('button').addEvent('click',function(){
    var time = new Date().getTime();
    new Element('li', { text: 'New one at ' + time }).inject('foo', 'top')
});

$('foo').addEvent('click:relay(li)', function(){  
    alert(this.get('text'));
});

<button id="button">Add an Item</button>
<ul id="foo">
    <li>Beef Jerky</li>
    <li>Smoked Salmon</li>
    <li>Rocky Mountain Oysters</li>
</ul>

jsFiddle