Do you get a reward for answering questions on WikiAnswers?
WikiAnswers is a community-based Q&A website. They look to their users to ask and answer questions. If you mean by just answering questions anytime, you can get the Premier Answerer badge if you answer quality answers, but that's about it.
In a WikiAnswers AnswerThon, if you answer enough questions you can get a prize (individual prizes are listed for each individual AnswerThon). AnswerThons are announced on the orange banner on the WikiAnswers homepage.
In addition, for many contributors of this site, the reward is knowing that you have helped out somebody else. Answering questions can help you learn new things.