Hi Alan,
I've got to agree: it's sort of like asking someone to provide a detailed guide to the culture of Java and Sumatra. New Guinea considered probably
the most linguistically diverse region in the world, so there isn't one culture. From what I've read, the major problem the PNG government is currently facing is trying to get this mass of independent humanity to come together into a single national identity.
Couple of random books:
Anthony Meyer's
Oceanic Art turned out to be a fairly interesting tome that people were selling cheap last year. It's somewhat useful for identifying artistic motifs and such. (edit: I agree with Detlef. Our posts came out simultaneously)
If you're after anecdotes,
Throwim Way Leg is a great read.
If you have some more specific questions, probably someone will be able to provide more focused help.
Best,
F