gistfile1.rb

# keywords_controller.rb
class KeywordsController < ApplicationController
  def new
    @domain = Domain.find(params[:domain_id])
    @keyword = @domain.keywords.new
  end
end

# domains/new.html.haml
%h1= @domain.name

= link_to @domain.url, @domain.url
%br
= link_to "Edit this domain", edit_domain_path(@domain)

%h2 Keywords
= link_to "New keyword", new_domain_keyword_path(@domain)