Fwiw, William Gibson would visit the City of Darkness in search of inspiration for his dystopic cityscapes. Here's a description from Idoru (1997):
> There was a place near an airport, Kowloon, when Hong Kong wasn't China, but there had been a mistake, a long time ago, and that place, very small, many people, it still belonged to China. So there was no law there. An outlaw place. And more and more people crowded in; they built it up, higher. No rules, just building, just people living. Police wouldn't go there. Drugs and whores and gambling. But people living, too. Factories, restaurants. A city. No laws.
There's a book "Chasing the Dragon" by a English missionary (I think) that lived in the walled city. Nothing in the way of pictures, but pretty interesting details of daily life from her experiences there.
I particularly liked the WSJ multimedia feature / interactive story with video interviews of past residents at the top of your link:
http://projects.wsj.com/kwc/
Further links for interested people: "Gweilo" - book about a british son of expats growing up in Hong Kong, and includes his visits the KWC http://www.amazon.com/Gweilo-Memories-Hong-Kong-Childhood-eb...
The amazing maps made by a japanese team that went into the KWC just before it was destroyed. http://www.deconcrete.org/wp-content/uploads/2010/03/Kowloon...