var banner = new Array();

          banner.push('http://imageshack.us/a/img11/2140/itsmylife2.png');
          banner.push('http://imageshack.us/a/img29/7226/itsmylifecopie.png');

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

          setInterval("document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];",15000);