var banner = new Array();

banner.push('http://img714.imageshack.us/img714/5548/55679810.png');
banner.push('http://img651.imageshack.us/img651/4836/54748077.png');
banner.push('https://nsa19.casimages.com/img/2010/09/29/100929045500709027.png');
banner.push('http://img810.imageshack.us/img810/2591/83509935.png');
banner.push('http://img801.imageshack.us/img801/9261/16148384.png');

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