I spent many years writing that it was daft to type questions into search engines, because what you were really searching for was an answer. You’d get better results, I argued, by typing in any part of the answer you knew.
Despite the logic of this position, the market voted with its feet, and typing questions into search engines became a huge proportion of the queries received. This will of course increase as voice search becomes more common. The search engines have since poured enormous resources into ensuring they answer questions with instant answers. Having questions on your website (followed by the answers, of course) has become a strong SEO strategy.
The trend has proved to be fantastic for question-and-answer websites. Quora has been claimed to be in the world’s top 200 websites now. Yahoo Answers and Answers.com provide much the same service. So is it worth getting involved in these sites? Yes, but as ever with these things, it needs to be done properly and with some commitment.
The key is to become somebody who answers questions regularly. Join in the sites as a community member, and be respectful as well as helpful. I don’t think there’s anything wrong with setting up questions as well as answering them. Links from Q&A sites are normally tagged as ‘nofollow’, meaning that they shouldn’t be counted as links (or even followed!) by the search engines, but there have been recent changes in how Google treats these links, so they may have some direct link-building benefit. Much more importantly though, they’ll drive real traffic to your site. And if you have a better-presented answer than the Q&A site, I’m sure search engines will be discovering that through the link.