As someone who has served one tour of duty in Iraq and is getting ready to leave for another at the end of November, let me say that My War by Colby Buzzell is just about as close of a description as you can get to everyday life as a soldier in Iraq. The book started life as a blog and got picked up by Putnam; I bought the book and read it cover to cover in one day.
So, if you're interested in knowing what it's like, what everyday life is for us, then grab yourself a copy of this book, because it will put you right in the middle of a deployment without ever having to leave your recliner.
I'd second the recommendation for Ball Four without any reservations. Jim Bouton tells a really good story that actually leaves you wanting more. I'd also recommend Ron Luciano's The Umpire Strikes Back for those who like slightly more comedic books.