var j, images = new Array();

var folder = "/images/home/left/";

images[images.length] = "lftpic01.jpg";
images[images.length] = "lftpic02.jpg";
images[images.length] = "lftpic03.jpg";
images[images.length] = "lftpic04.jpg";
images[images.length] = "lftpic05.jpg";
images[images.length] = "lftpic06.jpg";
images[images.length] = "lftpic07.jpg";
images[images.length] = "lftpic08.jpg";
images[images.length] = "lftpic09.jpg";

j = parseInt(Math.random()*images.length);
j = (isNaN(j)) ? 0 : j;

document.write("<img src='" + folder + images[j] + "'>");