Reamde by Neal Stephenson

This book is a long, exciting spy and technology thriller. It starts with a virus launched against users of T'Rain, a game designed to make certain types of money-laundering possible. But when the virus hits the wrong users, it quickly involves the main characters in the global war on terror. The book is fast paced and it skillfully balances a wide cast of characters. There's some weird chivalry on the part of some of the characters, but otherwise I really enjoyed reading this story.