I finished C.S. Lewis' "The Screwtape Letters" last night, I read it straight through in two sittings and was disappointed when it was over. You should go straight to the library and get it out, or buy if you want, I've got the library's copy, but I'll be keeping my eye out for a copy I can add to my bookcase. This book would have to be one of the best books I've read in the last couple of years. (Admittedly if your not a Christian you may not enjoy it as much, but it is still probably worth a read)
Plot Overview
This book attempts to examine life from the perspective of a demon, Screwtape, by use of his letters too his nephew, Wormwood. Wormwood is a junior tempter that has been placed in charge of leading a specific human away from Jesus, while Screwtape is a more senior demon, giving him advice on how best to go about the tempting of this human. Many "tricks of the trade", so to speak, are exposed in these letters.