Sky-debug is a project mainly written in ..., it's free.
Trivial debug library
With this gem you can easily invoke IRB prompt anywhere in your application.
You are required to do just two things:
Include 'sky-debug' gem:
require 'rubygems'
require 'sky-debug'
Call it anywhere you like to get an IRB prompt:
breakpoint binding
And you'll get an IRB prompt anywhere in your program with all the environment context.
As I've said it is a gem. It is published on rubygems.org for your convenience. You can rake it yourself if you like. It depends on 'echoe' gem as a framework.