var mess = new Array('<img src="images/random1.jpg" height="400" width="240" border="0" alt="random image" />','<img src="images/random2.jpg" height="400" width="240" border="0" alt="random image" />','<img src="images/random3.jpg" height="400" width="240" border="0" alt="random image" />','<img src="images/random4.jpg" height="400" width="240" border="0" alt="random image" />','<img src="images/random5.jpg" height="400" width="240" border="0" alt="random image" />');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);