Book Rank
An interesting idea:
- Take a single book from Amazon as a root.
- Take the recommended books for that book.
- Repeat until you have reached a distance of 20 from the original book.
- Add up the number of recommendations for each book.
- Calculate the BookRank from the Distance, Recommendations and SalesRank
- Display the 250 books with the highest BookRank.
Some examples are available on their site. (via findability)