If you're entering business school this fall, or are just starting to prepare for the GMAT, there are certain books that are easy to read while giving you a good grasp of basic business-related concepts. BusinessWeek just wrote a piece featuring some of these books, based on recommendations from professors at a few top MBA programs.
There are a few usual suspects here, such as Goldratt and Cox's The Goal, which is required reading in many Operations classes (including my first-year operations course at Kellogg). That anyone could take Ops and turn it into a novel is a wonder. No one will mistake it for a John Grisham novel, but the authors do a good job of presenting Operations lessons in a pretty easily digestable format.
Other recommendations include Gladwell's The Tipping Point, Friedman's The World Is Flat, and Levitt and Dubner's Freakonomics, which is a popular title at Veritas prep headquarters. None of them is directly applicable to your first-year business school courses the way The Goal is, but each will give you a good mental workout and get you thinking about business matters in new ways.