Una cosa del genere:
codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Documento senza titolo</title>
<script type="text/javascript">
function AttivaForm(f){
document.getElementById('TastoUnico').value='invia '+f.id;
document.getElementById('TastoUnico').onclick=function(){document.getElementById(f.id).submit();
}
}
</script>
</head>
<body>
<div id="forms">
<form action="?form1" id="f1" onclick="AttivaForm(this)" method="get"><input name="testo1" type="text" /></form></p>
<form action="?form2" id="f2" onclick="AttivaForm(this)" method="get"><input name="testo2" type="text" /></form></p>
</div>
<input name="TastoUnico" id="TastoUnico" type="button" value="Per abilitare il tasto seleziona un form" /></p>
</body>
</html>