application_helper.rb

module ApplicationHelper
    #...
    def feature(name)
      if Feature.exists?(:name => name)
        Feature.find_by_name(name).deployed?
      else  
        Feature.create(:name => name, :deployed => false)
        false
      end
    end
    #...
end

features_controller.rb

class FeaturesController < ApplicationController
  before_filter :require_admin #this could be anything, just make sure only an admin can access this controller
    
  def index
    @features = Feature.find(:all)
    #use whatever layout you want. I decided to stick all of this in the admin section of my application
    render :layout => 'admin' 
  end

  def update
    if params[:feature]
      Feature.update(params[:id], params[:feature])
    end
    #I modified routes.rb to make this url work
    redirect_to '/admin/featues/index' #or redirect to an error page
  end

end

index.html.erb

<h1>Features</h1>

<table border="1">
  <tr>
    <td>name</td>
    <td></td>
  </tr>
<% @features.each do |feature| %>
  <tr>
    <% form_for feature, :url => '/admin/features/update' do |f| %>
      <input type="hidden" name="id" value=<%= feature.id %> />
      <td><%= feature.name %></td>
      <% if feature.deployed %>
        <input type="hidden" name="feature[deployed]" value="false" />
        <td><input type="submit" value="rollback" /></td>
      <% else %>
        <input type="hidden" name="feature[deployed]" value="true" />
        <td><input type="submit" value="deploy" /></td>
      <% end %>
    <% end %>
  </tr>
<% end %>
  </table>

some_controller.rb

def index
   @products = Product.find(:all)
   if feature("Everything Must Go")
     #take 90% off everything!
     @products.each {|product| product.price = product.price*(0.10)}
   end
end

some_view.html.erb

<% if feature("Time Machine") %>
   <%= render :partial => 'time_machine' %>
<% else %>
   <p>Our time machine is still in development. Check back soon!</p>
<% end %>