no_follow_back.rb

require 'rubygems'
require 'twitter'

auth   = Twitter::HTTPAuth.new('username', 'password')
base   = Twitter::Base.new(auth)
guilty = base.friend_ids - base.follower_ids

puts "There are #{guilty.size} People you follow who do not follow you"

guilty.each do |user_id|
  user = base.user(user_id)
  puts "#{user.name} follows #{user.friends_count} and has #{user.followers_count} followers."
end