Inspecting Ruby's internals: Nodewrap

A C extension for directly inspecting/manipulating the code in a running program
Example:
 1   irb(main):001:0> require 'nodewrap'
 2   => true
 3   irb(main):002:0> l = lambda { 1 + 1 }
 4   => #<Proc:0x401fbd78@(irb):2>
 5   irb(main):003:0> l.body
 6   => #<Node::CALL:0x401fa680>
 7   irb(main):004:0> l.body.members.each { |m| p [m, l[m]] }
 8   ["recv", 2]
 9   ["args", 2]
10   ["mid", 2]