Reading Beyond the Core, by Chris Zook. He says that when people see him reading it, they generally think it looks like a fun book, but it's not--it's for work and it's kind of dry. It's the sequel to Zook's Profit from the Core and is all about (from the website) "putting together combinations of adjacency moves into areas away from, but related to, the core business, such as new product lines or new channels of distribution."

His favorite book of all time--The Iliad.