var banner = new Array(); 
 
banner[0]='http://imageshack.us/a/img12/2708/logo1th.png'; 
banner[1]='http://imageshack.us/a/img526/6663/logo3wn.png';  
banner[2]='http://img40.imageshack.us/img40/2242/porta2.png';  
banner[3]='http://img266.imageshack.us/img266/8950/logo1ct.png'; 
banner[4]='http://img542.imageshack.us/img542/6531/logo2fa.png'; 

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