Опередил...
<!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'>
function test(Val) {
var o=document.getElementById('isert');
var dlm=(o.value=='')? '': '\r\n';
o.value=o.value+dlm+Val
};
</script>
</head>
<body>
<textarea id="isert"></textarea>
<select onchange='test(this.value);'>
<option value="insert test 1">1</option>
<option value="insert test 2">2</option>
</select>
</body>
</html>
</html>