var ajax = new Ajax.PeriodicalUpdater(
   'timeOnline',
   '/ajax/time.php',
   {
      method:'get',
      onComplete: showUpdates,
      frequency:60,
      onSuccess: function() {
         new Effect.Pulsate('timeOnline');

      }
});
function showUpdates(req)
{
   $('timeOnline').innerHTML = req.responseText;
}