Steve Pavlina has one essay, in particular, which changed the way I thought about my business and directly contributed to my later success. (The five-second version: improvements in your funnel are multiplicatively effective. Does that sound obvious? It wasn't obvious to me, and it set me down the road of A/B testing and other hillclimbing, and I climbed my way right out of my day job.)
Yes, he later went seven flavors of kooky... but no amount of kooky retroactively disproves good ideas. That's also a level of discourse which I'd prefer to avoid on HN.