http://www.ramonfincken.com/permalink/topic187.html

<?php
/**
 * Created on 19-okt-2009 -- 20:42:29
 * package_name -- cron.php
 *
 * This cron.php file integrates all WordPress functions/classes/plugins in order to perform your own cronjob
 * Secured with a configurable password
 * Cron will sent a "cron start" and a "cron end/succes" email to a log adress
 *
 * @author Ramon Fincken http://www.ramonfincken.com http://www.websitefreelancers.nl http://www.creativepulses.nl
 *
 * Call from Plesk:
 * wget -O /dev/null -q http://www.site.com/cron.php?auth=[your_auth_pw]&action=[your_action]
 *
 * More on cronjobs: http://www.ramonfincken.com/tag/cron.html
 * Pseudo cronjob: http://www.ramonfincken.com/permalink/topic86.html
 *
 */
$auth_pw = 'some_password';
$cron_log_email = ''; // Leave empty if you don't want to sent mails

if (isset ($_GET['auth']) && $_GET['auth'] == $auth_pw && isset ($_GET['action'])) {
   $action = $_GET['action'];
   if(isset($cron_log_email) && !empty($cron_log_email)) mail($cron_log_email, 'cron start', 'cron start');
   if (extension_loaded('zlib')) {
      $z = strtolower(ini_get('zlib.output_compression'));
      if ($z == false || $z == 'off')
         ob_start('ob_gzhandler');
   }

   if (file_exists('./wp-load.php')) {
      require_once ('./wp-load.php');
   } else {
      if(isset($cron_log_email) && !empty($cron_log_email)) mail($cron_log_email, 'cron error', 'Could not find or open wp-load.php');
   }

   if ($action == 'action_1') {
      // Do something here

   }
   elseif ($action == 'action_2') {
      // Do something else :)

   }

   if(isset($cron_log_email) && !empty($cron_log_email)) mail($cron_log_email, 'cron end', 'cron end');
}
?>