Q&A sites (like Quora, Yahoo Answers) are a great source of keyword ideas. Specially Quora is more popular these days.

Quora has many benefits :
– You can get better & trending keyword ideas.
– You can drive high-quality traffic for your website by putting your site link in your answers.
– You can promote your business product/services.

Quora is getting more popular every day. so you can start using this awesome platform right away.