Let me talk about a gem library which casts a spell on your Rails app and enables you to build your Rails app “on the fly” just like editing a Wiki. This is named “hocus_pocus”, and developed as an “isolated engine” for Rails 3.1. The “isolated engine” feature has been developed by Piotr Sarnacki (@drogus) as the RubySOC project #14 and is currently available on Edge Rails. I really appreciate him