From Wiki - GameHacking.org
Codemasters-Project ( or CMP for short) is a Game Enhancer centered website. It's one of the internet's top code hacking websites. There are plenty of hacking tools and understandable hacking guides (some contain images to make them easier to follow) spanning several systems. Not only does the site have a talented group of hackers, their forum support is superb. Code creators, code porters, code converters and FAQ/Guide translators all frequent the forums and help respond to game hacking inquiries.
CMP and GameHacking.org are strongly allied, as CMP started at GameHacking.org, and its members are now responsible for a significant portion of the next-gen hacking that takes place at GameHacking.org.
The site is currently experiencing technical difficulties, and is currently down.