function randomStr($length) {
  $randomStr = "";
  $chars = array('2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z');
  while(strlen($randomStr) < $length) {
    $alt = rand(1,2) % 2;
    if (0 == $alt)
      $randomStr .= strtoupper($chars[rand(0, count($chars) - 1)]);
    else
      $randomStr .= $chars[rand(0, count($chars) - 1)];
  }
  return $randomStr;
}

$len = (int) 8; // 1 trillion+ is enough doncha think?

if (@strlen($_GET['len']) > 0) {
  if (strlen($_GET['len']) > 2)
    header('Location:./' . substr(urldecode(addslashes($_GET['len'])), 0, 2));
  $len = (int) substr(urldecode(addslashes($_GET['len'])), 0, 2);
}

$password = randomStr($len);

http://code.cshaiku.com/code_php_password_generator.php

Password Generator

PHP