I finished All Quiet on the Western Front recently and it was pretty much the best thing I've ever read, so continuing on that theme I picked up
Storm of Steel by Ernst Junger. Only read the introduction so far but it seems pretty good.
While I was at the book shop I also got The Art of War for £3 which isn't really something you can sit down and read for long periods of time but is very interesting none-the-less. Good coffee table/toilet book.