optgroup

<form action="musica.php">
<div>
<select>
<optgroup label="Artistas copyleft">
<option>Gonzalo Montero</option>
<option>Borjita</option>
</optgroup>
<optgroup label="Grupos copyleft">
<option>El muro de Berlín</option>
<option>Dr. Sapo</option>
</optgroup>
</select>
</div>
</form>