This is a great PS2 Demo by SoopaDoopa. This is source code to the demo that you can look through and get ideas of how to really take advantage of the PS2.
I am finally putting out another demo, this time it is actually somewhat decent. 3.2 Million lit, shaded polygons per second, using just EE-core + COP2.
No SCE libs were used in this, just use EE-GCC to compile if you feel like it.
Hopefully more of you will be able to do something now that this is out.