Question and Answers Activity is not only useful for SEO prospective but also helpful in real life. In this activity people ask questions to public and professional gives the answer. The question answers website / forum also provides the facility to put their link with the answers. And this is also help to increase traffic on your website.
You can find so many High PR website here, and you can get your answer here soon. I have listed few top website below please have a look if you are looking for these website.