function random_banner(){
  var i=0;
  banners = new Array();
  banners[0] = '<li><a href="#"><img src="global/img/empresa-destacada1.jpg" width="166" height="60" /></a></li>';
  banners[1] = '<li><a href="#"><img src="global/img/empresa-destacada2.jpg" width="166" height="60" /></a></li>';
  banners[2] = '<li><a href="#"><img src="global/img/empresa-destacada3.jpg" width="166" height="60" /></a></li>';
  today = new Date();
  i=today.getSeconds();
  n=banners.length;
  return banners[i-Math.round((i-1)/n)*n];
}
function random_banner2(){
  var i=0;
  banners = new Array();
  banners[0] = '<li><a href="#"><img src="global/img/empresa-destacada4.jpg" width="166" height="60" /></a></li>';
  banners[1] = '<li><a href="#"><img src="global/img/empresa-destacada5.jpg" width="166" height="60" /></a></li>';
  today = new Date();
  i=today.getSeconds();
  n=banners.length;
  return banners[i-Math.round((i-1)/n)*n];
}