Prova un po' così: dovrai chiaramente gestire meglio i tuoi dati, la mia vuole essere solo una traccia

codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script language="javascript" type="text/javascript">
function show_hide(c) {
  alert(c.name);
  document.getElementById(c.name+"field").style.display = (document.getElementById(c.name+"field").style.display=="none" ? "inline" : "none");
}
</script>
<title>Form Commenti</title>
</head>

<body>
<form name="form1" method="post" action="submit.php">
  <table width="600">
    <th width="100">Campo</th>
    <th width="200">Valore</th>
    <th>Commenti</th>
	<tr>
	  <td width="100">Cognome:</td>
	  <td width="200"><input name="cognome" type="text"><input name="cmmc" type="button" value="*" onClick="show_hide(this);"></td>
	  <td><div id="cmmcfield" style="display: none;">Commento Cognome:<input type="text" name="cmmcognome"></div></td>
	</tr>
	<tr>
	  <td width="100">Nome: </td>
	  <td width="200"><input name="nome" type="text"><input name="cmmn" type="button" value="*" onClick="show_hide(this);"></td>
	  <td><div id="cmmnfield" style="display: none; ">Commento Nome:<input type="text" name="cmmnome"></div></td>
	</tr>
	<tr>
	  <td width="100">Provincia: </td>
	  <td width="200"><select name="provincia">
      <option> </option>
      <option value="AO">AO</option>
      <option value="VE">VE</option>
      <option value="RM">RM</option>
      <option value="NA">NA</option>
      <option value="CT">CT</option>
    </select><input name="cmmp" type="button" id="cmmp" value="*" onClick="show_hide(this);">
    </td>
	  <td><div id="cmmpfield" style="display: none;">Commento Provincia:<input type="text" name="cmmprovincia"></div></td>
	</tr>
  </table><input type="submit" value="submit">
</form>
</body>
</html>