var banner = new Array();

banner.push('http://img651.imageshack.us/img651/967/doyourred.png');
banner.push('http://img821.imageshack.us/img821/9514/doyourredsport.png');
banner.push('http://img821.imageshack.us/img821/1954/doyourredgeek2.png');

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