production.rb

# config/environment/production.rb
require File.expand_path('../boot', __FILE__)

require 'rails/all'

# If you have a Gemfile, require the gems listed there, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(:default, Rails.env) if defined?(Bundler)

module Example
  class Application < Rails::Application
  ...
  # Enable serving of images, stylesheets, and javascripts from an asset server
  config.action_controller.asset_host = "http://dl.dropbox.com/u/123456/example.com"
  ...
end