added an invisible captcha to prevent spam

.gitignore

@@ -9,3 +9,8 @@ config/deploy.rb
 #eclipse
 .project
 .settings
+
+.rvmrc
+
+#rubymine
+.idea

app/controllers/users_controller.rb

@@ -1,7 +1,8 @@
 class UsersController < ApplicationController
   before_filter :require_no_user, :only => [:new, :create]
   before_filter :require_user, :only => [:show, :profile, :edit, :update]
-
+  before_filter :form_span_control, :only => :create
+
   def new
     @user = User.new
   end
@@ -38,4 +39,14 @@ def update
       render :action => :edit
     end
   end
+
+  private
+
+  def form_span_control
+    unless params['ruby_creator'] == 'Yukihiro Matsumoto'
+      render :text => "Please make sure cookies and js are enabled"
+      return false
+    end
+  end
+
 end

public/javascripts/application.js

@@ -2,4 +2,8 @@
 // This file is automatically included by javascript_include_tag :defaults
 $(function() {
 	$("#datetime").datetimepicker({showOn: 'button', buttonImage: '/images/calendar.gif', buttonImageOnly: true });
-});
+});
+
+$(document).ready( function(){
+  $('#new_user').append( '<input type="hidden" id="ruby_creator" name="ruby_creator" value="Yukihiro Matsumoto">');
+})