One essay of mine demonstrably created more economic value than everything I've done in ~15 years of my career. Probably combined.
The most useful essay, measuring by citation count in legitimate journals, is an HN comment which I posted on my blog because it was getting long.
It spawned a small genre.
kalzumeus.com/2012/01/23/sal… <-- people tell me this has gotten (cumultatively) high 7 figures in raises (and that's just what I know about)
kalzumeus.com/2010/06/17/fal… <-- was almost going to be this HN comment: news.ycombinator.com/item?id=1438355