I've posted an Affiliate marketing example showing a way to create a search page for multiple affiliates programs. A few noteworthy notes:

1) The affiliate search results are displayed on your website so that if your visitor doesn't find anything interesting in their searches, they're still on your site.

2) Default search terms relevant to my target market are automatically entered when you first arrive at the page--having the page filled with results by default means that there's content for the search engines to see and index. Plus, if you have an idea of what your visitors might be looking for, you needn't waste an opportunity by showing them a blank page when they arrive.

3) Multiple merchant sites can be searched from the same page, increasing the probability of your visitors finding something they're interested in. At the moment, the example code only searches Amazon and All Posters. More merchants will be added later.

4) Google AdSense ads appear on the page--if you don't reach your visitors in one way, you might reach them in another.

5) The example requires Grouper Evolution. As it appears on my site, it also requires CaRP Evolution, but could be easily adapted to the other versions of CaRP. With CaRP Koi, the AdSense add could not appear inside the search results (because without the FlexFormat plugin, more ads than Google allows would be displayed). With CaRP GPL, the images could not be displayed.

6) Finally, the "method" for the search form is "get". This is important if you have AdSense ads on the page, because without it, Google couldn't deliver relevant ads based on the visitor's search terms.