Preso direttamente da freephp, l'unica cosa ho modificato la lingua perché prima era tutto in inglese. Bastava comunque cercare un pochino
http://freephp.html.it/script/lista.asp?idcat=16

codice:
<html>
<head>
<title>Calendario</title>

</head>
<body>
<?
define ('ADAY', (60*60*24));
$datearray = getdate();
$month = $datearray['mon'];
$year = $datearray['year'];

$start = mktime(0,0,0,$month,1,$year);
//echo $start;
$firstdayarray = getdate($start);
//echo $firstdayarray['mon'];

$months =  Array('Gennaio','Febbraio','Marzo','Apri
 le','Maggio','Giugno','Luglio','Agosto',
 'Settembre','Ottobre','Novembra','Dicemb
re');
$days =  Array('Dom','Lun','Mar','Mer','Gio','Ven
','Sab');

?>
<table border=1 cellpadding=1 bordercolor="000000" cellspacing="0" align="center">
  <tr> 
    <td colspan="7" bordercolor="ffffff"> 
      <div align="center"><font color="#000066"><font face="Verdana, Arial, Helvetica, sans-serif" size="2"> 
	   <? echo $months[$month-1]." ".$year ;?>
		</font></font></div>
    </td>
  </tr>
  <?

foreach($days as $day)
{
?>
  <td bordercolor="ffffff"> 
    <div align="center"><font color="#000066"><font face="Verdana, Arial, Helvetica, sans-serif" size="1"> 
      <? echo"$day";?>
      </font></font></div>
  </td>
  <?
}
for( $count=0;$count<(6*7);$count++)
{
	$dayarray = getdate($start);
	if((($count) % 7) == 0)
	{
		if($dayarray['mon'] != $datearray['mon'])
			break;
		echo "</tr><tr>";
	}
	if($count < $firstdayarray['wday'] || $dayarray['mon'] != $month)
	{
		echo "<td bordercolor=ffffff>
</td>";
	}
	else
	{
		if($dayarray['mday'] == $datearray['mday'])
		{
			
			
			$var = date('d/m/Y');
		?>
  <td bordercolor="#FF0000"> 
    <div align="center"><font face="Verdana, Arial, Helvetica, sans-serif" size="1"> 
     <? echo $dayarray[mday]; ?>
      </font></div>
  </td>
  <?
				$start += ADAY;
		}
		else
		{
	?>
  <td bordercolor="ffffff"> 
    <div align="center" class="content"><font face="Verdana, Arial, Helvetica, sans-serif" size="1"> 
      <? echo $dayarray[mday]; ?>
      </font></div>
  </td>
  <?
		$start += ADAY;
		}
	}
}
?>
  </tr>
</table>
</body>
</html>
bye