Going to switch it to amazon.com!

Yes, totally agree! We're going to make adjustments to the algorithm so that books by the same author show up less (obviously if I'm searching for Harry Potter I'm probably not looking to be recommended six other J.K. Rowling books).

Is this just an item-item collaborative filter based on star ratings and cosine distance or do you have something more sophisticated going on?

Hey! Wanted to let you guys know that we use Amazon data and currently the Amazon API limits the request rate so that if there's multiple concurrent visitors it might be temporarily delayed. Working on fixing it now!

Rate-limiting task queue and aggressive caching might help out... "Shown HN" loosely translates to "DDoS Me" :P

Yeah, at the very least slap a leaky bucket on there. https://en.wikipedia.org/wiki/Leaky_bucket

Also, a user navigating to /search/:title is currently shown a raw error .json that exposes both your HMAC signature and your AWS access ID