Hard for me to answer that.
I'm really much more of an information person than a fiction reader.
But if he
hasn't got much into Douglas Adams or Terry Pratchet, that's always a good place to go, but lots of people read those... I'd imagine he's already read 1984 as well, but that's one of my favorite books.
See, I just read Guns, Germs, and Steel in three days, so like I said, I really go more for that kind of thing...