function openwin(){
   var rand_url= new Array()
   rand_url[0]="http://www.demosweb.it";
   rand_url[1]="http://spettacolo.lasiciliaweb.it";
   rand_url[2]="http://www.ngextra.it";
   rand_url[3]="http://salute.lasiciliaweb.it";
   var rand_num= Math.floor(Math.random()*4);

   var win = window.open(''+rand_url[rand_num]+'','lasiciliaweb','top=2000,left=2000,width=100,height=100');
   win.blur();
}