I came across this nice visualization of “Top 29 books ranked by unique users linking to Amazon in Hacker News comments“.
Amazon product links were extracted and counted from 8.3M comments posted on Hacker News from Oct 2006 to Oct 2015.
Most of these are, not surprisingly, on programming and design. A few are on startups and business. Some are on how to have a good life. Which is a bit weird.