Congratulations to billionaire Sam Walton and talk-show host David Letterman, whose trucks have been chosen for the Ugly Pickup Hall of Fame in Chadron, Neb. Walton, the Bentonville, Ark., resident who started the Wal-Mart store chain and once was regarded as the richest man in the country, drives around in a noisy 12-year-old pickup, and Letterman makes frequent references to owning a beat-up truck of his own on "Late Night." Les Mann, publisher of the Chadron Record newspaper, has established the Ugly Pickup Hall of Fame in the snackroom of his newspaper building and says he is seeking pictures of more ugly pickups to include.