var banner = new Array();

banner.push('https://img10.hostingpics.net/pics/922174Header.png');
banner.push('https://img10.hostingpics.net/pics/799025header2.png');
banner.push('https://img10.hostingpics.net/pics/931254header2.png');
banner.push('http://img718.imageshack.us/img718/6682/khyssian2.jpg');

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