I love this book. :D The Atrocity Archives collection combines Lovecraftian Horror with Len Deighton style cold war style spy thrillers, and has a pinch of Dilbert thrown in for good measure. The books centers on Bob Howard, a lowly computer nerd working for The Laundry, the super-secret British agency that deals with paranormal, demonic, and various otherworldly threats. Though his job primarily entails keeping the office computers up and running, Howard made the mistake of expressing an interest in field duty. Because magic and summoning in this world is all very mathematical, scientific and regimented, Howard's unique skillset and nerd cred make him uniquely qualified for certain tasks, and he finds himself thrown into increasingly dangerous missions involving possessed terrorists, necromantic Nazi holdovers from World War II, and world devouring monsters. This is on top of the peril he faces from his evil, soul sucking, pointy-haired supervisor at The Laundry. Luckily our protagonist is up for the challenge.
The main story from the Atrocity Archives collection, the The Concrete Jungle, is available online under the creative commons licence. I'm about to finish The Jennifer Morgue, the sequel to The Atrocity Archives. It's has more of an Ian Flemming/James Bond flavor, and is also quite good. Stross also has another Lovecraftian style Cold War story online called A Colder War , though this story takes place in a different universe and is written in a different style. Amusingly, Ollie North makes an appearance here.