var mess = new Array(
'<img src="images/banners/001.jpg">',
'<img src="images/banners/002.jpg">',
'<img src="images/banners/003.jpg">',
'<img src="images/banners/004.jpg">',
'<img src="images/banners/005.jpg">',
'<img src="images/banners/006.jpg">');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);