var banner = new Array();

banner[0]='https://i.servimg.com/u/f46/15/16/19/52/cmeban10.png';
banner[1]='http://img46.imageshack.us/img46/8569/soumassa.png';
banner[2]='http://img255.imageshack.us/img255/5791/xisxite.png';


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