<script language="JavaScript">
<!--
function RecogerDatos() {
    document.formulario3.result.value = document.formulario1.select1.options[document.formulario1.select1.selectedIndex].value + ' ' +  document.formulario2.select2.options[document.formulario2.select2.selectedIndex].value
}
//-->
</script>
<form name="formulario1">
<select name="select1" onChange="RecogerDatos()">
<option value="0">Cero</option>
<option value="1">Uno</option>
<option value="2">Dos</option>
<option value="3">Tres</option>
<option value="4">Cuatro</option>
<option value="5">Cinco</option>
<option value="6">Seis</option>
</select>
</form>

<form name="formulario2">
<select name="select2" onChange="RecogerDatos()">
<option value="Valencia">Valencia</option>
<option value="Alicante">Alicante</option>
<option value="Murcia">Murcia</option>
<option value="Madrid">Madrid</option>
<option value="Barcelona">Barcelona</option>
</select>
</form>

<form name="formulario3">
<input type="text" name="Resultado">
</form>