class Module
  def included_in_classes
    classes = []
    ObjectSpace.each_object(Class) { |k| classes << k if k.included_modules.include?(self) }

    classes.reverse.inject([]) do |unique_classes, klass| 
      unique_classes << klass unless unique_classes.collect { |k| k.to_s }.include?(klass.to_s)
      unique_classes
    end
  end
end