How Do You Drown Out the Office Noise?

An anonymous reader asks: "We've recently had yet another office re-organization, which is not so bad in itself, but the noise level has increased significantly due to the type of furniture as well as job functions of those whom I share the office with. The first thing I think I'm going to do is to get a pair of noise canceling headphones, but before I spend hundreds of dollars I'd like to hear some opinions or alternatives. Two of the ones that look neat are the Extreme Isolation Headphones and Plane Quiet Headphones. What have others done to cope with noise level?"