Opera or classical music. Sometimes Jazz.
When flying, I listen to great operas, including:
Puccini: Madama Butterfly, Tosca, La Boheme
Wagner: Der Ring Des Nibelungen("The Ring" for all you unwashed heathens), Tristan und Isolde, Parsifal, The Flying Dutchman, Lohengrin, Die Meistersinger von Nurnberg.
Korngold: Die Todt Stadt, Das Wunder der Heliane, Violanta.
Massenet: Werther, Manon, Thais.
Also, I'm a huge fan of Gustav Mahler, so I usually listen to his symphonies a great deal while flying AH or just sitting at the computer.
Oh yeah, the soundtrack to "This is Spinal Tap" is fun for a change of pace!
