You’ve probably heard of Quora. If not, you need to check it out. It’s an incredible resource of in-depth information, knowledge, advice and insight, much of it unavailable in such a format anywhere else, with a vast number of talented and creative people participating. As Techmeme editor Mahendra Palsule wrote in 2010, “There is no other service on the web today with such a high signal-to-noise ratio, period.”
But, be warned: you can easily lose hours on the site. It’s like Wikipedia with a focus on individual contributions; what Knol was meant to be. It’s easily the best question and answer site on the internet, because in contrast to sites like Yahoo Answers and Answer.com, which are usually dominated by simple factual answers (that can be found even quicker with a Google search), Quora is focused on discussions, opinions, original research, and firsthand experience.