Another good Leica info resource is http://www.butkus.org/chinon/leica.htm - a lot of manuals and instructions. I bet most of you are familiar with this one though

Also, here are the very extensive on-line price guides for Leica cameras and lenses. They aren't as good as McKeown's or Kadlubek's, but not everyone has McKeown's guide at home
http://collectiblend.com/Lenses/Leitz/
http://collectiblend.com/Cameras/Leitz/