var i=1, container=$('<div>'), addToList=$('#addToList'); addToList.after(container); container.append('<select id="dropDown" size="10" style="width:200px">'); addToList.click(function(){ $("#dropDown").append($('<option />').text('Item '+i++)); });
<input type="button" id="addToList" value="Add to List" /><br/>