var banner = new Array();

banner[0]='https://i.servimg.com/u/f42/16/02/23/00/lanin10.png';
banner[1]='https://i.servimg.com/u/f40/16/30/89/64/lanin_10.jpg';
banner[2]='http://img191.imageshack.us/img191/3997/lanin2.jpg';

document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];