People are one of the greatest inventions ever! If you have a question or a problem and pose it as such, people will go out of their way to help you or find the information you need. This is one of the biggest reasons that knowledge management practitioners emphasize knowledge sharing (people sharing with people), rather than knowledge bases (people sharing with computers). People want to help each other, and the best time is when there is an immediate question or inquiry, rather than some possible future question.
And this is the genesis of Question and Answer websites, such as the current phenom, Quora. Quora isn't the first, and probably won't be the last system to enable these kinds of interactions. Facebook has set up a "questions" service (that I'd like to remove from my sidebar!). LinkedIn Answers and Yahoo Answers have been running a couple years. There are also Answers.com and Otavo and Mahalo. Yedda has become AOL Answers. Google turned off its Answers service, as have FAQQLY and Wondir and LazyWeb (a variant). I am sure there are many others, both alive and dead. I had written on this topic a few years ago, and there was another a long list from 2006. And beyond these general websites, there are thousands of discussion forums and community-run spaces which are used in exactly the same way: I have a question about XYZ, so I go visit the XYZ forum and learn. (Or I go to ten XYZ forums and see which people seem to talk in a language that I can understand.) Quora is creating interest in the topic again, from the business model of Q&A services to the specifics of their model. But the underlying human nature is the same.
There will never be an end to people asking questions, so there will never be an end to services that offer a means to ask and answer those questions.
[Photo: "Question mark in Esbjerg" by Alexander Henning Drachmann