From Wiki - GameHacking.org
The Game Shark Hackers Index
GSHI is a longstanding collaborative group of gameshark and action replay code hackers who have contributed many, many codes to the scene. The website and forums were started by and are currently coadministrated by the member who calls himself Lazy Bastard. Many people who use the gameshark and the action replay devices are unaware that the companies who manufacture and market those devices use websites and communities such as GSHI to produce and distribute the codes that cause the hacking devices to be as popular as they are.
The website is located here: http://www.thegshi.org
The community itself gathers at the website's home forums, located here: http://www.thegshi.org/vb/