All the devils are here by Bethany McLean and Joe Nocera, about the Wall Street crash. It is a more complete account than some of the earlier books, and doesn't put all the blame on one or two actors or factors. The thesis is that there were a LOT of villains and no heroes.
The Ghost of Cannae: Hannibal and the darkest hour of the Roman republic, by Robert O'Connell, about the Punic Wars. Very interesting, lots of insight about the Romans and the Carthaginians.