Link to the Show / Show NotesYesterday's combative appearance of Howard Stern on Late Night with David Letterman lasted three freewheeling segments, sparing few media heavyweights. There were some tender moments. Stern mainly used the appearance to settle old media scores, sharpening his rhetorical knives on his archnemeses: Don Imus, Dr. Phil, Oprah Winfrey and Jay Leno.--On Letterman's supposed fascination with ham radio: Stern said, ''Listen to me ... a lot of serial killers are ham radio operators.''