function random_product(){
  var productimg=new Array()
  //specify random images below. You can have as many as you wish
  productimg[1]="images/product/product_1.jpg"
  productimg[2]="images/product/product_2.jpg"
  productimg[3]="images/product/product_3.jpg"
  productimg[4]="images/product/product_4.jpg"
  productimg[5]="images/product/product_5.jpg"


  var rn=Math.floor(Math.random()*productimg.length)

  if (rn==0)
     rn=1
     document.write('<img src="'+productimg[rn]+'" width="310" height="363" border="0" />')
}