Some people may find that most tutorials are a bit steep in terms of the assumptions made about the knowledge of the reader. If this is the case, the reader probably needs to master some of the basics, before moving on to more intensive parts of PS2 development.

A great tutorial describing the PS2's architecture, different avenues one might take in beginning PS2 development, ways to execute code on the PS2 once you're written and/or compiled it, and including a history of PS2Dev. A must-read for anyone entering the scene.

A great guide for beginners, going into quite a bit of detail as to how to get started developing PS2 homebrew, including links to good MIPS ASM and C programming reference, answers to many common questions, and explanations of the different methods of executing and testing your compiled binaries on a real PS2 or emulator. Definitely take a look at this if you're justing starting out.