Have you ever finished a book and wanted your next read to be similar? Maybe you read a detective novel, set in 1920s Detroit, and you really got into that era and the language and imagery. It takes a long time to walk into a book store (or Amazon) and read the jackets of every book in the mystery section until you find one that looks good.
Instead, go to WhatShouldIReadNext.com, type in the name of the last book you read (or the author, or the ISBN number) and VOILA! Two or three suggestions for similar books appear. In many cases, there is also a link to purchase the book.