app_config.yml

# config/app_config.yml
---
defaults: &defaults
  :name: Super Awesome Blog
  :tagline: My super awesome blog and stuff.
  :email: you@example.org

development:
  <<: *defaults
  # Override the defaults.

test:
  <<: *defaults
  # Override the defaults.

production:
  <<: *defaults
  # Override the defaults.
  :tagline: My super awesome blog, in production!

init.rb

# config/init.rb
Merb::BootLoader.after_app_loads do
  # This will get executed after your app's classes have been loaded.
  begin
    config_file = File.expand_path(Merb.root + '/config/app_config.yml')
    AppConfig = YAML.load_file(config_file)[Merb.env] unless defined? AppConfig
  rescue => error
    puts 'AppConfig could not be loaded!'
    puts error
  end
end