Studentquestions.com : If you are an experienced teacher then you have the opportunity to earn online answering questions on different subjects.While registering you choose a subject that you are proficient in.When a student asks a question in a category,that question will be sent to all the registered members of that particular category.After you answer the question the student has the option of buying the best answer.

ExpertBee :This site pays for your expert answer. For Experts answering information questions, the commission schedule is $0.60 + 20% of the fee.
For Experts providing services, the commission is a one-time fee of $7.95 paid at the time you win the question.

Just Answer :If you are an expert in any field then you can get paid for answering questions.As a new expert you get 25% of the amount that a customer offer.Above average experts get 50%.

BitWine :Get paid for providing consultation on Technology, Nutrition, Travel, Relationship, Parenting etc.

SmallBizAdvice : Get paid for sharing your business expertise and knowledge.

KnowBrainers : Get paid for answering questions on varieties of subjects.

ChaCha :Another site that pays to answer.But available only to the US citizens.

Web Answers :Get paid for your expertise.Get paid for your answers being selected as the best answer.