Affliate Question

I have been using a couple of organisations to boost banner advertising, and am now trialing affliates on one of my sites.

Is there such thing as an Affliate optimiser? Ie an organisation that can help to place the best affliate ads on my site in exchange for a % of income? Mo nitoring the market and switching campaigns to get the best money?

I’ve tried CJ and a few others - but its pretty hit and miss, how can I find someone with experience to work together on this basis?

Thanks