Amazon has announced that their ContextLinks product is now in beta and is available for their affiliates to put into use.
ContextLinks reads the context of your page, and then changes any phrases on your page into relevant links to Amazon products with your affiliate ID so you get commissions. You simply place one piece of code on the page and it does this automatically. It’s a pretty low effort way to possibly earn affiliate commissions. You can see ContextLinks in action at Muppet Central News, they are the underlined links in the article text.
This should work well on sites that are heavily product focused where a system like AuctionAds.com works well.