(answer from mcapri sumbitted by emk)
Looks like I found a few resources. What I didn’t find was one comprehensive ranked list of everything. Barnes and Noble shows their top 100 on their website http://www.barnesandnoble.com/bestsellers/top100.asp
The NYT bestseller list shows only the top 5 without registering which is simple and free of charge, once registered you can see the top 35 in a given category http://www.nytimes.com/pages/books/bestseller/
The American Booksellers Association also has charts of bestselling books: http://www.bookweb.org/booksense/bestsellers/
And finally for Amazon.com there is a website devoted entirely to ranking items sold there called junglescan. What you have to do is cut and paste the URL of a book or amazon item in question into the box marked for that purpose. It is important to click on the particular item and not to cut and paste the URL of search results into the box Here’s the URL: http://www.junglescan.com/
Also if you need to trace these statistics backwards and cant find such a on the website itself try plugging the URLs into the wayback machine at:
mcapri