This is the orignal, see the new one

hook.rb

class Hook < ActiveRecord::Base
  attr_accessible :event, :account_id, :subscription_url, :target_url
  validates_presence_of :event, :account_id, :subscription_url, :target_url

  # Looks for an appropriate REST hook that matches the record, and triggers the hook if one exists.
  def self.trigger(event, record)
    hooks = Hook.find(:all, :conditions => {
        :event => event,
        :account_id => record.account_id,
      })
    return if hooks.empty?

    unless Rails.env.development?
      hook = hooks.first
      Rails.logger.info "Triggering REST hook: #{hook.inspect}"
      RestClient.post(hook.target_url, record.to_json) do |response, request, result|
        if response.code.eql? 410
          Rails.logger.info "Destroying REST hook because of 410 response: #{hook.inspect}"
          hook.destroy
        end
      end
    end
  end

end

hook_test.rb

require 'test_helper'
require 'fakeweb'

class HookTest < ActiveSupport::TestCase

  def setup
    @account = Factory(:account)

    @subscription_url = "https://zapier.com/hooks/standard/wpGRPPcRxZt2GxBbSSeUAlWPBnhLiRWB/"
    @target_url = "https://zapier.com/hooks/standard/wpGRPPcRxZt2GxBbSSeUAlWPBnhLiRWB/"

    hook = Hook.create(
      {
        "event" => "new_contact",
        "account_id" => @account.id,
        "subscription_url" => @subscription_url,
        "target_url" => @target_url
      }
    )

    @contact = Factory(:contact, :account => @account,
      :first => 'Ryan', :last => 'Porter', :email => '[email protected]')
  end

  def test_trigger
    FakeWeb.register_uri(
      :post,
      @target_url,
      :body => 'irrelevant',
      :status => ['200', 'Triggered']
    )

    Hook.trigger('new_contact', @contact)

    assert_equal "POST", FakeWeb.last_request.method
    assert_equal @contact.to_json, FakeWeb.last_request.body
  end

  def test_trigger_remove_hook_on_410_response
    FakeWeb.register_uri(
      :post,
      @target_url,
      :body => 'irrelevant',
      :status => ['410', 'Danger, Will Robinson!']
    )

    Hook.trigger('new_contact', @contact)

    assert_equal "POST", FakeWeb.last_request.method
    assert_equal @contact.to_json, FakeWeb.last_request.body

    assert_equal 0, Hook.count # The 410 response should trigger removal of the hook.
  end

end

hooks_controller.rb

class HooksController < ApplicationController
  def create
    hook = Hook.new params
    render :nothing => true, :status => 500 and return unless hook.save
    Rails.logger.info "Created REST hook: #{hook.inspect}"
    # The Zapier documentation says to return 201 - Created.
    render :json => hook.to_json(:only => :id), :status => 201
  end

  def destroy
    hook = Hook.find(params[:id]) if params[:id]
    if hook.nil? && params[:subscription_url]
      hook = Hook.find_by_subscription_url(params[:subscription_url]).destroy
    end
    Rails.logger.info "Destroying REST hook: #{hook.inspect}"
    hook.destroy
    render :nothing => true, :status => 200
  end
end

hooks_controller_test.rb

require 'test_helper'

class HooksControllerTest < ActionController::TestCase

  def setup
    @account = Factory(:account)
    @user = Factory(:user, :username => 'username') # Password: "password", by default.
    @staff = Factory(:staff, :account => @account, :user => @user)
  end

  def test_subscribe_requires_authentication
    post :create,
      {
        "event" => "new_contact",
        "subscription_url" => "whatever",
        "target_url" => "whatever"
      }

    assert_redirected_to :controller => 'public/signin', :action => 'signin'
  end

  def test_subscribe
    @request.env["HTTP_AUTHORIZATION"] = "Basic " + Base64::encode64("username:password")

    subscription_url = "https://zapier.com/hooks/standard/wpGRPPcRxZt2GxBbSSeUAlWPBnhLiRWB/"
    target_url = "https://zapier.com/hooks/standard/wpGRPPcRxZt2GxBbSSeUAlWPBnhLiRWB/"

    post :create,
      {
        "event" => "new_contact",
        "account_id" => @account.id,
        "subscription_url" => subscription_url,
        "target_url" => target_url
      }

    assert_response 201
    assert_equal 1, Hook.count

    hook = Hook.last
    assert_equal %Q[{"id":#{hook.id}}], @response.body
    assert_equal "new_contact", hook.event
    assert_equal @account.id, hook.account_id.to_i
    assert_equal subscription_url, hook.subscription_url
    assert_equal target_url, hook.target_url
  end

  def test_subscribe_error
    @request.env["HTTP_AUTHORIZATION"] = "Basic " + Base64::encode64("username:password")

    post :create, nil

    assert_response 500
    assert_equal 0, Hook.count
  end

  def test_unsubscribe_rest
    @request.env["HTTP_AUTHORIZATION"] = "Basic " + Base64::encode64("username:password")

    hook = Hook.create(
      :event => "new_contact",
      :account_id => @account.id,
      :subscription_url => 'whatever',
      :target_url => 'whatever'
    )
    assert_equal 1, Hook.count

    post :destroy,
      {
        :id => hook.id.to_s,
        :subscription_url => 'whatever'
      }

    assert_response 200
    assert_equal 0, Hook.count
  end

  def test_unsubscribe_the_hacky_way
    @request.env["HTTP_AUTHORIZATION"] = "Basic " + Base64::encode64("username:password")

    subscription_url = "https://zapier.com/hooks/standard/wpGRPPcRxZt2GxBbSSeUAlWPBnhLiRWB/"
    target_url = "https://zapier.com/hooks/standard/wpGRPPcRxZt2GxBbSSeUAlWPBnhLiRWB/"

    Hook.create(
      :event => "new_contact",
      :account_id => @account.id,
      :subscription_url => subscription_url,
      :target_url => target_url
    )
    assert_equal 1, Hook.count

    post :destroy,
      {
        "subscription_url" => subscription_url
      }

    assert_response 200
    assert_equal 0, Hook.count
  end

  
end

FYI: I updated the original fork just now to support triggering REST hooks from Resque background jobs.

Updated the main fork again to check for an applicable hook before enqueuing a Resque job.

And to run ALL applicable hooks (instead of just the first match).

And to demonstrate using Resque-Retry for dealing with Resque worker jobs that run before the transaction is closed. If you're using Rails 3 then use "after_commit :do_something, :on => :create" instead.