Some are ones you see coming up a lot: The Mom Test, Designing Data-Intensive Applications, Refactoring UI, Don't Make Me Think.
But then some were just way off my radar, like the writings of sociologist Edward T. Hall or Stephen Baxter's sci-fi.
I also bought a lifetime subscription for an app I found here, but mostly it was books.
What did you buy after reading a recommendation on HN?
The Pyramid Principle
The Mom Test
Concepts, Techniques, and Models of Computer Programming -- this one so recently that my copy hasn't even arrived yet. I think I found out about it literally like maybe 3 days ago or so.
The Master and Margarita
Solaris
The Gervais Principle
Not sure if I've ever bought anything besides books based off of an HN recommendation or not. Thinking about it, I'd guess probably at least once, but if so I can't recall what it was now.
Probably a couple books related to software as well, but the above really stand out.