New Christmas-themed pop songs do appear every year, and Thunder Bay, Ont.-native Paul Shaffer says it's no surprise why artists keep trying to record a new modern classic.

Hidden in the attention being paid to David Letterman leading to his May 20 retirement is the knowledge that it will also mean the end of a regular television role for America's bandleader, Ontario-born Paul Shaffer.

To mark Letterman’s retirement revelation, here is a Top Ten list of memorable moments from his shows.