I know that Amazon has a new contextual ad feature that adds relevant product links to your site's text,as well as their Omakase link script, but I came across something that looks a bit more promising and versatile.

TicTap Contextual Ads allow you to create context blocks for your site that can be displayed in your left or right column. There's also a likelihood that the ads can be placed within articles and posts using div tags if you follow some of the tips you'll find here and also here

Here's the url to the script:
http://www.tictap.com/tca