var msg = new Array(); 
msg[0] = '<div><a href="http://www.nileport.com/jump/index.html?id=1459" target="_blank"><img src="http://cn.nileport.com/images/common/300x100higankaku.jpg" width="300" height="100" alt="飛雁閣" border="0"></a></div>';
var no = Math.floor(Math.random() * msg.length); 
document.write(msg[no]);