Вот, например мой пример
<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<!--
<link rel="stylesheet" type="text/css" href="tmp.css" />
-->
<style type="text/css">
</style>
<script type="text/javascript">
$(document).ready(function(){
$('#add').click(function(){
var val
val='<div>'
val+='<select name="work_type1">'
val+='<option value=""></option>'
val+='<option value="1">Item 1</option>'
val+='<option value="2">Item 2</option>'
val+='<option value="3">Item 3</option>'
val+='</select>'
val+='</div>'
$('#test').append(val)
});
});
</script>
</head>
<body>
<form id='frm' method='get'>
<div id='test'></div>
<input id='add' type='button' value='Add' />
<input type='submit' value='Send' />
</form>
</body>
</html>
Формирует вот такой УРЛ
http://<url>?work_type1=1&work_type1=2&work_type1=3