Pay Per Click Search Engines, or PPC SEs are a great tool for advertisers. Basically, this is a search engine like any other but built in favor of advertisers who want to pay money in order to be seen. Pay-per-click search engines work by having people bid against each other for certain keywords. For example, if you outbid anyone for the keyword "money", your website will appear first whenever a user types in the word "money" into the search engine's search form.

In other words, you can buy the first position for a certain keyword. Each time a surfer clicks on this keyword, the advertiser pays the PPC SE a few cents.
I guess you all know that.

The other side of the coin is that PPC SEs also need traffic. Otherwise no one is going to click the keywords that the advertisers have previously bidded for. That's why Pay Per Click Search Engines are eager to share a part of their revenue with sites who display search results on their pages.

Bottom line: If you have a busy site that has lots of visitors, you may get some good amount of money if you display results from pay per click search engines.

Working with Pay Per Click Search Engines is much more profitable than working with traditional Pay Per Click programs.