you should check it google adwords. but as far as i know anything related to bank loan or lawyer is high paying.
Unique content and traffic from Google search engine will help you to earn more, no matter whatever niche your website is in!
It is always the same ones - Real Estate, Finance, loans, lawyers, health and fitness, consolidation, structured settlement, medical transcription, etc.
adwords is costly for newbies and if you are not clear you may lose your investment in adwords. but you can try adwords with coupons initially...