List named sub-modules of a module.

named_submodules.rb

module NamedSubmodules
  def named_submodules
    constants.map{ |c| const_get c }.select{ |c| c.is_a?(Module) && c.const_defined?('SUBMODULE_NAME') }
  end

  def named_submodule_list
    named_submodules.inject({}) do |hash, mod|
      hash[mod.to_s] = mod.const_get('SUBMODULE_NAME')
      hash
    end
  end
end

Module.send :include, NamedSubmodules