Paid XML feed and monetization.

Hi, I’ve recently heard of paid xml feeds which can be placed in the site just like google search box. and if someone uses the search box and gets a result, a click on those result may yield money.
How the advertisers or feed provider pays per click? do they have any bidding system in place? or a default bid system. I am very curious to know.
Last but not least, who all are providing these kind of paid xml feeds? may i know.
Pls help.

See original post by RGguy