By Pete Sampras and Lindsay Davenport, the Wimbledon singles titles, Sunday. Their wins mark the first time in 15 years that Americans took both titles. It was Sampras's sixth Wimbledon crown and Davenport's first . . . By 50-year-old American Steve Keiner, a 317-pound electrical inspector from Atlantic City, N.J., the Mustard Yellow International Belt, for eating 20 1/4 hot dogs in 12 minutes, Sunday, at Nathan's Hot Dogs, Coney Island, N.Y., although there is some question as to whether or not he jumped the (ahem) bun.