Amazon's associates program offers web site publishers a fairly quick and easy way to generate some extra income from product recommendations. Currently, the program pays commissions starting at 4% (or as Amazon says, "up to 8.5%") on sales generated from traffic you refer through an affiliate link. The cool thing is you get commissions on the entire sale, so even if you refer someone to a $2.99 box of cereal (good stuff) you'll earn commissions on the entire order.

Not surprisingly, people tend to click (and buy) most often on links that are relevant to the topic of the page they're reading. So is there a way to automatically present links that are relevant to the page? Here are three ways it can be done.

1. Use your site's tagging system to generate relevant recommendations. Amazon's "Recommended Product Links" ad format allows you to select a keyword and/or category, then let Amazon serve appropriate product recommendations onto your site. The nice thing about this is Amazon will keep their ad current, so you won't find yourself advertising products that are out of stock or no longer produced.

One trick I use on this site is to dynamically serve category names into Amazon's ad code to create relevant book recommendations near the end of each category page. For example, the bottom of our VoIP category page includes the following copy and advertising:

I figure if someone has reached the bottom of that page, they're ready for their next move. In this case, I've given them the option of visiting VoIP information at del.icio.us, Technorati, or Google News along with six book recommendations from Amazon. The Amazon links are dynamically generated based on the category.

To do this, pick the ad format you'd like to use on Amazon Associates, enter a keyword, then generate the code. Before including it in your site, swap out the keyword with the code used to generate categories.

2. Use Omakase Links. Amazon has a new ad format in beta that will generate product recommendations on the fly for any web page. Similar to Google AdSense, it takes a look at the content of a page, then serves up relevant ads. But rather than being ads for other web sites, they're product recommendations from Amazon's extensive catalog.

3. Use an Ad Rotation Script. Chris Garrett over at Performancing recently published a tutorial on how you can auto-rotate the keyword variable in your Amazon ad code using PHP. This seems like a good choice if you want to limit your advertising to a group of product choices you've deemed relevant to your audience.