var banner = new Array();

banner[0]='http://i28.tinypic.com/2upvjvp.jpg';
banner[1]='http://i32.tinypic.com/2qjd4y9.jpg';
banner[2]='http://i25.tinypic.com/j9na78.jpg';
banner[3]='http://i26.tinypic.com/5frhgp.jpg';
banner[4]='http://i29.tinypic.com/2nknz1u.jpg';
banner[5]='http://i32.tinypic.com/10scbwh.jpg';
banner[6]='http://i30.tinypic.com/4fznrn.jpg';

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