var banner = [];

banner[0]='http://img697.imageshack.us/img697/2676/hidankakuzubanner.png';
banner[1]='http://img560.yfrog.com/img560/2417/hachibibanner.png';
banner[2]='https://i.servimg.com/u/f21/15/81/01/51/nwu-ba10.jpg';
banner[3]='http://img440.imageshack.us/img440/2899/nwubanner2.png';
banner[4]='http://img132.imageshack.us/img132/8412/nwubanner3.png';
banner[5]='http://img8.imageshack.us/img8/9112/sasoribanner.png';
banner[6]='http://img413.imageshack.us/img413/8974/yondaimebanner.png';

var bannerLength = banner.length-1;

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

setInterval("document.getElementById('i_logo').src= banner[Math.floor(Math.random()*bannerLength)];",9000);