The delightfully motley crew that is Diamond Rugs — John McCauley (Deer Tick), Robbie Crowell (Deer Tick), Ian Saint Pe (Black Lips), Hardy Morris (Dead Confederate), Steve Berlin (Los Lobos) and Bryan Dufresne (Six Finger Satellite) and others — rocked out last night on The Late Night with David Letterman stage with a spirited rendition of Blue...