var banner = new Array();

banner.push('http://img685.imageshack.us/img685/5281/tomorrow.png');
banner.push('http://img708.imageshack.us/img708/3717/tomorrowtiiucopy3.png');
banner.push('http://img651.imageshack.us/img651/2724/tomorrowboyd.png');

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