lì credo sia fatto con il db cmq
codice:
<?php
$path = "percorso/ai/file";
$file_php = array();
if ($handle = opendir($path)) {
   while (false !== ($file = readdir($handle))) { 
       if($file != '.' && $file != '..' && !isDir($path."/".$file)) {
              list($name, $ext) = explode(".", $file);
              if($ext == 'php') {
                  $file_php[] = $file;
              }
       }
   }
}
closedir($handle); 
echo "File php:".count($file_php)."
";
foreach($file_php as $name) {
    echo $name."
";
}
?>