I don't usually write book reviews, as they often help comprise the banality that is typical of most web logs, however this book is so unique and enjoyable that I will make an exception.
For the student of ancient or of military histories, this book is especially recommended. Gates of Fire, by Steven Pressfield, is the self-described Epic Novel of the battle of Thermopylae, where Leonidas and several thousand Greeks held off the two million man Persian invasion, and in doing so, guaranteed themselves a place in immortality. The book has the realistic feel of works like Black Hawk Down, as it includes details of Spartan life and military training. It definately breathes life into historical accounts of the battle, allowing the reader to come much closer in spirit to the Lakedaimonians (Spartans).
One word of caution: This is a book which takes a realistic look at the brutality of ancient warfare. As such, don't expect the characters to speak for polite company whilst hacking each other apart. As do many of the "rough men stand ready to do violence on [our] behalf" as George Orwell supposedly said, these rough men of Greece speak rudely when appropriate. Add to that the brutal violence of Greek warfare, and this is a book not for all audiences. But for someone who wants to get closer to the Battle for the Hot Gates, I can think of no better text.