Matt Kahn is undertaking to read and review every book on the Publishers Weekly annual bestsellers list from 1913 onwards. You can see his progress and the list of books on his blog.
I took a quick look through the list and i'm struck by how many books and authors I've never heard of - like The Good Earth by Pearl S. Buck, which topped the charts in 1931-32 and also won the Pulitzer. I'm also surprised about some of these results. I mean, Johnathan Livingston Seagull was the best selling book in America for two years straight? The Tommyknockers - most definitively NOT Stephen King's best book - was the most popular book in 1987? And it's disheartening to remember just how many people read the taught plots and lazy prose of John Grisham and Dan Brown. I was also surprised to see some film books - what seem to be adaptations of E.T. and The Return of the Jedi - on the list, but read Kahn's note that Harry Potter books are not included in the PW bestsellers for some reason. (For the record, the Harry Potter books make for excellent reading.)
An interesting project!