class UserManager(models.Manager):
    def __init__(self, *args):
        try:
            self.fk_field_name = args[0]
        except IndexError:
            self.fk_field_name = None

        super(UserManager, self).__init__()

    def get_query_set(self):
        query_set = super(UserManager, self).get_query_set()
        
        if self.fk_field_name:
            current_user = get_current_user()

            if current_user and not current_user.is_superuser:
                return query_set.filter(**{ '%s__exact' % self.fk_field_name: current_user })

        return query_set

# Example usage

class TestModel(models.Model):
    owner = models.ForeignKey('auth.user')
    objects = UserManager('owner')