Everyone have a Facebook account and huge friends in the friend list. Managing friends is not as easy as you manage your followers on Twitter. There are hundreds of tools and services to find out who followed and unfollowed you, but that is not the case with Facebook.
If you find your friends number going down, its not that easy to find out who exactly unfriend your. So here is a simple 'greasemonkey' script that will do exactly what you want.
Unfriendfinder is a user script that make a list of your friend and check it every-time you refresh your Facebook account. Is that simple. It will start working from second use and not as soon as you install it because there is no any list to compare with. It can also find who have deactivated or deleted their own Facebook account.