If you haven’t yet read Neal Stephenson’s novel Snow Crash, I highly suggest you do. Some of the events in the book can be paralleled to real life situations (particularly issues such as hyper-inflation and corporate owned city-states or “burbclaves”). But, this novel would also make for a great movie. The major issue is determining who would match the personalities of the many unique characters.
Naturally, this list is incomplete, and focuses on the more important roles in the novel.
Hiro Protagonist: Almost certainly I would cast Will Smith in this role. Hiro is not particularly nerdy; in fact, his attitude is more suited towards Will Smith than anyone else.
Y.T.: “Yours Truly” would need to be played by someone who can act the “punk” role; I would go with Anna Paquin, who played “Rogue” in the X-Men films.
Yes, I do realize that Y.T. is a bit younger than Anna Paquin.
Juanita Marquez: I don’t know why, especially since Juanita is a small role, but I would cast Catherine Zeta-Jones here.
Da5id Meier: Jeff Goldblum; the role fits him perfectly.
Dr. Emanuel Lagos: I know, I’m really pulling some of these people from Independence Day, but Brent Spiner would be great here, playing the techie doctor.
Uncle Enzo: This is tough; I would have to say Robert De Niro. He has the same tough guy/nice guy persona that Enzo possesses.
The Librarian: The old “man” who helps Hiro do research while in the Metaverse would be best played by Morgan Freeman.
Raven: Someone big and powerful would fit this role nicely. Michael Clarke Duncan, from Sin City, The Green Mile, and The Whole Nine Yards, would be best suited to the role.