var banner = new Array();

    banner.push('http://i56.tinypic.com/287qc6u.png');
    banner.push('http://i54.tinypic.com/2vafv48.png');
    banner.push('http://i56.tinypic.com/o6b58z.png');
    banner.push('http://i53.tinypic.com/2zth941.png');
    banner.push('http://i51.tinypic.com/nycs4l.png')

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