Mine

<?

 $dir = $_GET['dir'];

?>

<form method="get">
  <input name="dir" type="text" value=<?echo('"' . $dir . '"');?>/>
  <input value="ls" type="submit" />
</form>

<hr/>

<?php
  if ($dir == '')
    die;

  $dirlist = scandir($dir);

  foreach ($dirlist as $item)
    echo '<a href="./_ls.php?dir=' . urlencode($dir . '/' . $item ) . '">' . $item . "</a><br />\n";
?>