.irbrc for logging goodies like SQL/Mongo queries to $stdout if in Rails 3 console

.irbrc

# .irbrc to log goodies like SQL/Mongo queries to $stdout if in Rails 3 console
if defined?(Rails) && Rails.respond_to?(:logger)
  require 'logger'
  Rails.logger = Logger.new($stdout)
  if defined?(Mongoid)
    Mongoid.logger = Rails.logger
  end
end

Pop this snippet in your ~/.irbrc to show the raw JavaScript queries that Mongoid is running as you play with your app in the Rails console (and/or SQL, if you’re using ActiveRecord). Formatting isn’t great for Mongo queries, but it’s helpful nonetheless.
http://crumbtrail.chesmart.in/post/1334264255/handy-bits-for-mongoid-with-rails-3