I'm a one person shop so I have to keep it simple for now... no international orders, no backorders. If I ever decide to expand, of course I will ship internationally, but still would not allow backorders. I might have "Out of Stock" on the description page, no "add to cart" button, but one that says "please notify me when this item becomes available." That way they will know right away that this order will not include that item and they may look for another item just to fill up a box to save on shipping.
Also, I try to delete any items that are out of stock ASAP if I know I'm not reordering it. That way the customer won't spend time drooling over it then find out it's all gone. If I am reordering an item, I may move it back to the "coming soon" category until I receive it.