Use QT and Webkit to manipulate the DOM

gistfile1.rb

require 'Qt'
require 'qtwebkit'

class Viewer < Qt::WebView

  slots 'change_h1()'

  def initialize(parent = nil)
    super(parent)
    connect(self, SIGNAL('loadFinished(bool)'), self, SLOT('change_h1()'))
  end

  def change_h1
    document = page.mainFrame.documentElement
    document.findFirst('h1').setPlainText('Fuck Yeah')
    document.findFirst('img.avatar').setAttribute('src', 'http://3.bp.blogspot.com/_4-k4YH3MeeE/TSpkNodQS5I/AAAAAAAAAhY/lvehzszHOuM/s400/fuck_yeah_.jpg')
  end

end

a = Qt::Application.new(ARGV)
v = Viewer.new
v.load Qt::Url.new('http://www.pioz.it/')
v.show
a.exec