application_controller.rb

class ApplicationController < ActionController::Base

  helper_method :page_title,
                :page_description

# ...

end

dyn_meta_config.yml

 en:
  <meta key pluralized>:
   <controller>:
    <action>:
     <id>: "Some meta value"

dyn_meta_example1.yml

 en:
  page_titles:
   users:
    new: "Create Your Account"
    edit: "Update Your Account"

dyn_meta_example2.yml

 en:
  page_titles:
   pages:
    show:
     tos: "Terms of Service"
     pp: "Privacy Policy"
     about: "About My Site"

dyn_meta_example3.yml

 en:
  page_titles:
   default: "My Super Site"
   users:
    default: "Manage Your Account"
    new: "Create Your Account"
    edit: "Update Your Account"

dyn_meta_imp1.html.erb

 <title><%= page_detail(:page_title) %></title>
 <meta name="description" content="<%= page_detail(:page_description) %>" />

dyn_meta_imp2.html.erb

 <title><%= page_title %></title>
 <meta name="description" content="<%= page_description %>" />

users_controller.rb

 def show
  @user = User.find(params[:id])
  page_detail(:page_title, "#{@user.display_name} :: Profile")
 end