var banner = new Array();
banner[0]='http://img132.imageshack.us/img132/4629/foroooa.jpg';
banner[1]='http://img705.imageshack.us/img705/7480/bannerdqts.png';
banner[2]='http://img855.imageshack.us/img855/4662/bannerexamenes.png';
banner[3]='http://img135.imageshack.us/img135/696/bannerparanoia.png';
banner[4]='http://img200.imageshack.us/img200/8760/bannerpasapalabra.png';
banner[5]='http://img638.imageshack.us/img638/9414/bannersoftcombat.png';
banner[6]='http://img189.imageshack.us/img189/1028/bannerviaje.png';

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