Here is an interesting presentation that can be found on YouTube.
“100 Greatest American Stamps” presented by Janet Klug and Donald Sundman, The Sixth Annual Maynard Sundman Lecture, February 9, 2008, Smithsonian National Postal Museum. The museum’s Maynard Sundman Lecture Series was established in 2002 through a donation by his sons, David and Donald. The Sundman lectures feature talks by authors and expert philatelists on stamps and stamp collecting. Visit: http://www.postalmuseum.si.edu/Sundman