Label de Option da tag select
<html>
<head>
<script type="text/javascript">
function label_option( el )
{
var label = el.options[ el.selectedIndex ].text;
alert( label );
}
window.onload = function()
{
document.getElementById( 'teste' ).onchange = function()
{
label_option( this );
}
}
</script>
</head>
<body>
<form action="" method="post">
<label>Teste: <select name="teste" id="teste">
<option value="">--</option>
<option value="1">Um</option>
<option value="2">Dois</option>
<option value="3">Tres</option>
</select></label>
</form>
</body>
</html>
referência: