plugins.rb

module Plugin1
  def some_method
    puts "ha!"
  end
end

module Plugin2
  def some_method_again
    puts "hrn..."
  end
end

module PluginContainer
  def self.included(base)
    base.extend(ClassMethods)
  end
  
  module ClassMethods
    include Plugin1, Plugin2
  end
end

class Wooooo
  include PluginContainer
end

Wooooo.some_method
 => "ha!"