For the longest time, there were two companies about which I couldn’t understand all the fuss: Foursquare and Quora.

I still have never gotten much into Foursquare, although I have spent enough time with Dennis Crowley that I’m rooting for him as a fellow entrepreneur. But over the last few months, I have found myself really falling in love with Quora — but not for the reasons you might think.

Last week, I sat down with the site’s co-founders Charlie Cheever and Adam D’Angelo for a 90 minute exclusive interview. That may be a record for the ultra-shy duo, who rarely grant media requests and prefer to let the site speak for itself. I asked for the meeting because, as a user, I was finding Quora increasingly more interesting just as other tech journalists were saying it had peaked. As it turns out, I’m not alone in my interest. D’Angelo tells me that the site’s traffic hit an all time record last week and has been surging over the last six months, breaking record after record.

What’s driving it? An astounding diversification beyond just tech news that’s mostly happened while the blogosphere wasn’t looking. The company recently looked at five different categories of answers: Business and technology, food and entertainment, politics and social sciences, health and life advice, and “other.” The first four drive almost exactly the same amount of content on Quora — a fact the founders confirmed in a post a few minutes ago.

Engagement shows an even bigger divergence from the early tech adopters. A well up-voted answer is more likely to be about movies than startups. A great new answer is more likely to be about parenting than it is to be about Facebook or Apple put together. In the past three months, the two topics drawing the most up-voted answers were movies and food.

The gushing over Quora by the classic early adopters was originally due to the quality of the answers from high profile techies being so astoundingly good. As a journalist who spends my day talking to many of these people, that was my least favorite aspect of the site: I wanted them to talk to me first, damnit!

But still, in the past few months, some of the best stuff I’ve read anywhere on the Web has been on Quora. This one by JJ Abrams on shooting movies as a kid stands out strongly in my memory, but there are many, many others. This one made a big impact too: What it feels like to write a movie that is panned for bad writing. It puts such a human face on a bomb, such that I never felt right Tweeting about bad film writing again.

Tech insights didn’t do it for me. Those are my stock and trade. But getting to see a window into the soul of Hollywood people I’d never get to meet? “Oh God. This is what people were gushing about a few years ago,” I thought.

What’s interesting to me is that the answers are about more than celebrity. The JJ Abrams stuff is cool, but you don’t find that everyday on the site. It was pretty much just around the release of “Super 8″. A lot of the other celeb answers are by the omni-Web-present Ashton Kutcher.

And really, we can get enough of celebrity on the Web — most notably on Twitter. What stands out are the answers from people buried deep inside the Hollywood machine. One recent answer that captivated Cheever: What are actors actually snorting when they pretend to do cocaine? (Answer: It’s frequently powdered sugar and actors report everything tasting sweet for the rest of the day.)

That’s the kind of stuff you can get on Quora that you can’t get anywhere else. It’s like having a good friend in the film industry, or I presume, the tech industry for those who don’t spend their days inside of it already. It’s less about Reed Hastings answering your questions — he has too much to lose by being blunt. It’s more about a guy from Netflix answering them. The everyday people that actually create the products, sites, and movies we love. The previously nameless and faceless parts of the machine that know where all the bodies are buried and are just “unimportant” enough to be honest.

There has been plenty of speculation that Quora could replace journalism because CEOs can respond directly to the public, but it is this kind of insight — sometimes random, sometimes profound — that media can’t compete with. We can get the CEO on the phone, but these people are harder. They’re more difficult to track, partly because we don’t know who they are, but also because while they might not be keen to talk to a reporter, Quora allows them to share their expertise on their own terms.

Social media does that too, of course. But many of these people don’t have time to blog every day and they’re too unknown for regular folks to follow on Twitter. And yet, these are the people whose answers are captivating me the most. And I just wouldn’t have heard from them in a Quora-free world. Confessions of a nameless screenwriter just doesn’t sell copies of US Weekly.

And that’s why, as the rest of the tech early adopters have yawned and moved on, for a lot of regular folks, Quora is only now getting really, really interesting.

On the downside the fan boys and cynics like me shared the same fear: Does Quora scale this high level community and expand beyond tech? Many insisted that it couldn’t.

There were plenty of reasons to fear for the future of Quora. Hype about user-generated content aside, very, very few sites have convinced people to generate quality, long-form content en masse. In fact, it seemed that only Wikipedia and Yelp had figured it out.

The record of scaling a community of people ranking quality content was equally spotty. There were two curses Quora could easily fall victim to: the curse of Digg and the curse of Yahoo Answers.

Even in a Web where you have to hunt like a Truffle-seeking pig to find an example of crowds being wise, the lack of insight offered by Yahoo Answers users is mind-blowing. This is a community where “I don’t know! Good luck!” is considered a perfectly legitimate answer to a question.

If you don’t know, why did you answer the question! I’ll tell you why: Because ranking on Yahoo Answers goes up the more questions you answer. So quantity without quality are expressly rewarded. Not surprisingly, the quality is awful.

When it came to Digg, mainstream users were put off by a rowdy geeks-in-dungeons crew of power Diggers who largely held the site hostage. The management team catered to their demands most of the time, unfortunately.

These crowds-source-the-truth efforts always start well enough, and then almost always devolve as they grow. Another reason for the Quora frenzy in the early days may have been the fear in the pit of the tech world’s stomach: We’ve seen this movie before. There is simply no way this can last. Let’s enjoy it while we can.

Back when we were all so worried, two people were not: Cheever and D’Angelo. They knew Quora would scale.

Not that everything went according to plan from the start: They tried actively seeding new content areas with paid contributors, but this didn’t really take off. “It wasn’t the best use of resources,” says Cheever. Meanwhile areas they never invested in — like dating advice — grew uncontrollably. They learned to embrace what they couldn’t control.

In fact, there is no viral coefficient or easily reproducible answer here. The key is simply the DNA of the site. Unlike Yahoo Answers which emphasized quantity or Diggers that incentivized individual ego, Quora has always focused everything about its community, product, and business around finding the best possible answer for a question.

Early on, this caused an uproar among early adopters, when the answers or reposes of those posing the questions weren’t automatically given a higher ranking. Quora also seeks to group similar questions into one feed. Once something is entered into Quora, it become part of the collective seek towards the best answer — not property of the person who wrote it.

There are two golden rules to the site: Answer the question and be nice. Quora’s tech brains don’t think an algorithm can solve all of this. It’s a human-computer hybrid solution. The secret sauce of the company — if there is one — is knowing what a machine can do well and what you need a human for.

That’s a core belief of many of the companies that have spun out of Facebook. An example of the former is remembering what was entered into the system before or aggregating votes for an answer. An example of the latter is knowing two disparate questions are essentially trying to get at the same truth.

The company has a complex way of measuring something that a lot of people believe is fundamentally unmeasurable: Quality. “You can only measure things that correlate with quality, not quality itself,” says D’Angelo. Like the Colonel, the company will never divulge what those things are.

What Quora has gone through over the last two years is usually called the hype cycle and I’ve heard entrepreneur after entrepreneur trot it out as a reason the press cools on their story, while THEY SWEAR cool stuff is still happening, and it’s only a matter of time until they are surging again. The truth is most never do.

There are two differences with Quora: The first is that the company is actually growing The second is that Quora has sought to actively dampen the hype surrounding the company. “The hype wasn’t really helping us,” D’Angelo says. “It was a distraction and we needed to focus on scaling.” While the UI hasn’t changed much in two years, tremendous work has been done behind the scenes, Cheever says.

The company was practically born into the winners’ circle. It raised an $11 million series A at an unfathomable $86 million valuation back in 2010. That was largely because of the pedigree of Cheever and D’Angelo, both Facebook refugees. Cheever has typically been the company’s front man, but D’Angelo gets the credit for being the big tech brain behind it.

D’Angelo attended California Institute of Technology, where he graduated with a bachelor’s degree in Computer Science and a 4.0 grade point average. While in college, he was one of the top 24 finalists in the international Topcoder Collegiate Challenge. He also competed in the Association for Computing Machinery collegiate world programming contest. He placed second in 2004 and first in 2003. And in 2002, D’Angelo won the silver medal in the International Olympiad in Informatics.

I first met D’Angelo in the early days of Facebook, where he got another accolade. Mark Zuckerberg introduced him as the best programmer he’d ever met. He was cripplingly shy back then, making Zuckerberg look downright chatty. But when I met with them last week, he seemed articulate, confident, and relaxed — frequently jumping in to answer a question before Cheever could. D’Angelo might be the most important brain to watch in the Valley.

The two are still a challenge to interview. Every time you ask a question, Cheever pauses and scrunches up his face in a way that makes you think you are causing him physical pain. Their April Fools’ Day prank inside the company was an announcement that they were characters on Randi Zuckerberg’s PARTY DOWN SHIRTLESS MEN! new Silicon Valley reality show. You spend five minutes with them, and it’s hard to believe anyone on staff bought it.

The two were never quite comfortable with how Quora was thrust into the limelight. As two of the most respected members of the Facebook mafia — the brains that helped build essential early products like the Platform and the News Feed — they were born on third base. It would have been easy to maximize the buzz and do the speaking circuit, get the magazine covers, and most notably keep raising money at higher and higher valuations. But they wanted to earn their position on third base first.

Quora is rumored to be raising a new round of capital now. But then again, those rumors have been rampant throughout the last few years, and D’Angelo has addressed them on — not surprisingly — Quora. We used to regularly get tips to this effect at TechCrunch, and never ran the stories. Why? Because under closer examination, it was just wishful thinking. Various partners of firms who wanted to invest in Quora were leaking the information, hoping to spark a bidding war and convince the board the potential valuations were too high to ignore.

D’Angelo and Cheever wouldn’t comment on the current fundraising rumors. They may well be true — the company could raise money at any time, and as many a reporter has noted, it’s been two years since its series A. And the valuation will no doubt be a healthy one. Knowing these two, they won’t maximize the round for what they could get. They’ll go with the investors they want to work with.

But a lot of companies in the Valley can raise money at a nice valuation. Quora has quietly done something far more interesting: Made the crowds actually look wise.