David Letterman's 20th 'Late Show' anniversary: A photo album and more Bill

"Late Show with David Letterman" turns 20 Friday, but the celebration happened Thursday night. Here is one memorable moment -- a "photo album" of "Late Show's" gaudiest, nuttiest guests, visits, stupid pet tricks and a hundred other pieces of flotsam from a great run.

Plus, a few more clips from last night.

(And if you missed, you missed news -- the show's own hand-picked choice for the best top 10 entry of the last 20 years. The answer: "Clintern.") And what the heck -- we're on a roll here. Let's post Lenny Kravitz and Gladys Knight, too.)

(App users, watch the video at newsday.com/tvzone.)