At work we recently migrated from Sirsi Unicorn to Evergreen. In the process we lost some Sirsi provided content and our patrons let us know they were not happy. One of the complaints was the loss of the New York Times Bestsellers list. A quick Google search turned up the New York Times API.
http://developer.nytimes.com/
I've built a quick and dirty Drupal module which fetches the current lists from the New York Times and pulls book covers from Amazon. You can see the development version on the left.