function werbung() {
  var banners   = new Array();
  banners.push(new Array("http://www.krattingerag.ch/","banner/bestattung_krattigner.jpg"));
  banners.push(new Array("http://www.bierigmbh.ch/","banner/schreinerei_bieri.jpg"));
  
  var current   = banners[Math.round(Math.random()*(banners.length-1))];
  document.all('werbung_link').href   = current[0];
  document.all('werbung').src         = current[1];
}