studiVZ (German Facebook clone, something like six million members, 17 million if you add the other two VZ social networks) has always (or at least as far as I

studiVZ (German Facebook clone, something like six million members, 17 million if you add the other two VZ social networks) has always (or at least as far as I remember) allowed you to see who viewed your profile. You can opt-out so others won’t see you but you will still be able to see who viewed your profile.