var banner = new Array();

banner.push('http://img690.imageshack.us/img690/7443/banniereo.png');
banner.push('http://img690.imageshack.us/img690/7443/banniereo.png');
banner.push('http://img690.imageshack.us/img690/7443/banniereo.png');
banner.push('https://i.servimg.com/u/f13/13/23/69/09/treize11.png');
banner.push('https://i.servimg.com/u/f16/11/16/66/36/lul11.png');


document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];<code></code><br>