You can bet Facebook is storing that data though. And who knows what the future holds, perhaps Facebook will be forced to sell that data to its users in order to increase revenue and make stock holders content?
To be clear, it seems that the data exposed in this way is only affected by your own actions; i.e. it does not tell you who has been stalking you, just who you've been stalking.
In fact, there is an bookmarklet that shows the list: http://thekeesh.com/2013/03/updated-facebook-friends-ranking...