Rails project wide and personal configuration files

application.rb

require File.expand_path('../boot', __FILE__)
require 'rails/all'

module MyApp
  class Application < Rails::Application

    # you app configuration code

  end
end

{ :config          => :CONFIG,
  :database        => :DATABASE,
  :facebook        => :FACEBOOK,
  :mailer          => :MAILER,
  :paypal_adaptive => :PAYPAL,
  :s3              => :S3 }.each_pair do |file_name, variable_name|
  config   = YAML.load_file(File.join("#{Rails.root.to_s}/config", "#{file_name}.yml"))[Rails.env].symbolize_keys # Load in the defaults.
  override = File.join("#{Rails.root.to_s}/config", "#{file_name}.personal.yml") # Check for personal settings.
  config.merge!(YAML.load_file(override)[Rails.env].symbolize_keys) if File.exists?(override)
  self.class.const_set(variable_name, config)
end

# generates the following global constants:
# CONFIG
# DATABASE
# FACEBOOK
# MAILER
# PAYPAL
# S3

# don't forget to add config/*.personal.yml to your .gitignore

config.personal.yml

development:
  name: MyTotallySweetName
  host: lvho.st:3000
  user_dev_tweaks: true

config.yml

test:
  name: AppName
  host: 127.0.0.1:3000

development:
  name: AppName
  host: lvho.st:3000
  user_dev_tweaks: false

production:
  name: AppName
  host: sweetdomain.com