Two words: Good writing. The company just sold itself to AOL for a reported $30 million. Here's founder Michael Arrington's explanation of the sale:

I was tired of our endless tech problems, our inability to find enough talented engineers who wanted to work, ultimately, on blog and CrunchBase software. And when we did find those engineers, as we so often did, how to keep them happy. Unlike most startups in Silicon Valley, the center of attention at TechCrunch is squarely on the writers. It's certainly not an engineering driven company.

The emphasis is mine. I love that last tidbid because its a rare admission in Silicon Valley, where all start-ups—no matter what they do—are typically at great pains to explain themselves as technology companies. Technology is sexy, and talking about technology is a good way to sound like you know what you're talking about when you don't have a clue.

But not every company—not even every Internet company—is, at its core, a technology company. Zappos is a service company, for instance, and TechCrunch, as Arrington explains, is a writing company. 

Now compare Arrington's memo, to this one by the founder of a once promising start-up, Newstilt, which was founded by engineers who had limited writing experience:

The problem was that I didn't really know how the journalists should write their pieces, only a vague sense that it was wrong. I also didn't really want to tell them what to write, since they were doing us a favour by writing at all. In fact, we actively told them to write what they wanted. This could have been fine, if they had taken their cue from their readers. But we didn't really know who the readers were, and there weren't that many of them anyway.

I also think these two essays explain why so many media start-ups have struggled to generate actual, real-life profits. The Huffington Post, despite its size and its ability to get John Cusack to work for free, is still unprofitable. (2010 will be the year for profits, executives say. But then they also said that about 2009.) The same is true of Demand Media, which boasts some impressive technology, but still no profits.

In fact, when I try to think about other profitable media start-ups, like Gawker Media, which is the subject of a very nice profile in New York magazine, none seem particularly innovative, technologically speaking. They just publish darn good writing. 

Then again, you're talking to a writer, so maybe I'm biased. Would love to hear some counter-examples.