确实非常实用啊！

1. 用 app 来调用 routes，比如 app.posts_path, app.topic_path(1)

   irb > app.topics_path
   => "/topics" 
   irb > app.get(app.root_path)
   ......
   => 200 
   

2. 用 helper 来调用 Helper 方法，比如：

   irb > helper.link_to("Ruby China", "http://ruby-china.org")
   => "<a href=\"http://ruby-china.org\">Ruby China</a>" 
   irb > helper.truncate("Here is Ruby China.", length: 15)
   => "Here is Ruby..." 
   

3. 使用 source_location 方法查看方法在那里定义的，比如：

   irb >Topic.instance_method(:destroy).source_location
    => ["/Users/jason/.rvm/gems/ruby-1.9.3-p0/gems/mongoid-2.4.8/lib/mongoid/persistence.rb", 30] 
   irb >Topic.method(:destroy_all).source_location
    => ["/Users/jason/.rvm/gems/ruby-1.9.3-p0/gems/mongoid-2.4.8/lib/mongoid/persistence.rb", 239]
   

http://37signals.com/svn/posts/3176-three-quick-rails-console-tips