ARTS & ENTERTAINMENT TELEVISION Show Tracker Photos David Letterman's memorable guests "Late Show with David Letterman" has seen it all. Click through the nostalgia. By Christy Khoshaba This photo gallery is featured in these articles: Show Tracker David Letterman's retirement plans: A Ken Burns doc? Show Tracker Does David Letterman believe in spirits? Seems like it Pop & Hiss A Will Ferrell-Chad Smith drum-off on 'The Tonight Show'