You can count me as one of the long-term Quora detractors. To me, it's a good example of the "bubble effect". Everyone in the Valley thinks its huge because everyone in the Valley uses it. No one outside the Valley does (figuratively speaking). It's a thin social layer on what's just a Q&A site not that different to Yahoo Answers, which I guess is fine but I just don't see it going mainstream. As an aside, I've alway…
Isn't stack overflow in the top 100 sites in terms of traffic? While it might not be mainstream, it's already huge.
Google trends gives a better view. Here is is related to other sites that (according to Alexa) have similar traffic: http://trends.google.com/websites?q=stackoverflow.com%2C+dou...