The free and open source PlayStation 2 RAM Patcher & Remote Debugger has made some serious progress this month:
Functional RAM dumping for 60~70% of tested games.
Functional RAM patching for the games that work.
Mostly finished cheat code finding application.
And quite a few more in development features, such as a GUI made by Berion and code type support.
The end product of this project will be a fully-fledged RAM-hacking system and remote debugger, which will allow users to create their own cheat and enhancement codes for games, and debug games and applications. And of course it will be free.
If you're too poor or can't find a retail cheat device for the PlayStation 2, give Artemis a whirl!