By Brad Stone Oct. 14 (Bloomberg Businessweek) -- Is Quora just one more entrant in the already overpopulated category of question-and-answer sites on the Web? That's a question you will find on Quora itself, which last spring joined Yahoo! Answers (YHOO), Formspring, Aardvark, ChaCha, WikiAnswers (ANSW), and many others in providing a forum where Web users ask and answer queries online. Created by two former Facebook executives and funded by a third who became a venture capitalist, Quora has developed a loyal Silicon Valley following and a reputation as a hot, promising startup. The company has also morphed into something else: a bulletin board where Silicon Valley's most influential people routinely pack personal and professional insights into their answers. On Quora, you'll find Dustin Moskovitz, a Facebook co-founder, discussing his feelings about the film The Social Network ("It is interesting to see my past rewritten in a way that emphasizes things that didn't matter"), and Werner Vogels, Amazon.com's (AMZN) chief technology officer, debunking notions about why the online retailer got into cloud computing ("The excess capacity story is a myth"). Netflix (NFLX) CEO Reed Hastings, Craigslist founder Craig Newmark, and Digg founder Kevin Rose, among other Valley luminaries, are all users. "I'm actually impressed at the information that users are willing to volunteer," says Lada Adamic, an associate professor at the University of Michigan who studies social and information networks. "There are things on there that I would consider insider information for some of these companies." Co-founder Adam D'Angelo (left, in picture) roomed with Mark Zuckerberg at Phillips Exeter Academy and was Facebook's chief technical officer. He and Charlie Cheever, another Facebook colleague, left in 2008 to start Quora. Their mission: create a repository of knowledge that picks up where Wikipedia leaves off, and a site that can field the kind of detailed queries that Google (GOOG) gags on. "We want to get to the point where whatever question you have, you type it in, and there's already a great page of answers for you to look at," says D'Angelo, 26. The company has designed its site to reward serious discussion and cut down on the repetition that characterizes other Web Q&A services. Duplicate questions on Quora are combined. Users, whose professions are listed after their names, can revise other people's questions and vote answers up or down. They also can create discussion summaries that everyone else is invited to edit. "We want an answer page to present the best versions of all the different arguments that are important, with the most relevant and important answers at the top," says Cheever, 29. Cheever won't say how many users Quora has. According to researcher Compete.com, the site gets 150,000 visits a month, though its reputation in the Valley has grown faster than its traffic. More than 1,500 people RSVPd for a Quora community party last month, the company says, and invitees overpacked a San Francisco restaurant. Tech blogs religiously follow Quora's growth. Matt Cohler, a former Facebook executive and partner at Benchmark Capital, which led a $11 million investment in Quora in March, compares the site's appeal in the tech community to the early days of LinkedIn. "There's an extraordinarily high level of engagement and passion users have with the site," he says. The company itself is lean. Fourteen employees huddle around a lone, long rectangular table in an office over a downtown Palo Alto (Calif.) arts supply store. D'Angelo and Cheever, who tend to work late into the night, appear sleepy and shy in person. They declined to be photographed (they supplied the photo above), saying they prefer to keep the focus on the company. They'll need more than humility to push Quora beyond the insular borders of the self-involved tech world. The site is free and anyone can join. The interface can be daunting, though. With its voting buttons, nested comments, and links to related questions, Quora isn't as simple to use as other Q&A sites like Yahoo Answers and Answers.com (ANSW). Quora's biggest challenge may be its founders' former employer. Over the summer, Facebook launched a competing service, Facebook Questions. The Quora guys won't talk about that. Will Facebook get in the way of Quora's quest? That's another question on Quora, of course, with two well-reasoned answers by Valley residents taking different positions. No one has written that consensus summary yet. The bottom line: Q&A website Quora, a hit among techies, is trying to create a knowledge database that picks up where Google and Wikipedia leave off.