That's a good site. I've visited many times. I like the part about introducing new cats on opposite sides of a closed door. I thought that's what I was doing by letting Jackie and Charley see each other through the glass door of our kitchen most of the summer. All was going well and Jackie seemed to be looking forward to seeing his new friend everyday. The problem was Charley's reaction to being indoors for the first time. Jackie seems to know that I am not in the best of health and has become quite protective of me. When Charley started freaking out, I think Jackie took that as a threat to me and jumped into action.There are some good tips here: http://www.humanesociety.org/animals/cats/tips/introducing_new_cat.html
They are back to looking at each other through the closed glass door, but at this point my wife and I are looking into heated enclosures so Charley can just remain outside. That's not a definite plan though.