I will often mention books without posting an Amazon/etc. link figuring that anyone interested can bing with Duck Duck Google to find it. Other times, I will link to the author/publisher page.
Anyway, there's a natural language processing cum machine learning project in their somewhere. One interesting possibility it would open up is surfacing books in electronic form that pass across Hacker News as links to PDF's, eBooks, and HTML.
At least 12 of the books in the top 100 for 2015 are from my posts.