This tool is called AmaSenseAds and is very similar to AdSense. Well, it actually looks just as the regular AdSense ads, but instead of showing ads from the popular Google program, this one shows ads for various things sold at Amazon (books, dvds, appliances). I am not sure if you can chose what your ads should be showing or not, because I have actually never tried AmaSenseAds myself.
It looks very interesting and the potential to earn money is probably there, but my question is. If you have exactly the same look as AdSense ads, most people think that it´s an ad from AdSense. Do people really click that much on AdSense ads on regular sites? I know that we click a lot on AdSense ads on the Google search engine, but that´s different. A lot of people think that this is not sponsored searches and many click because the ads showing from AdSense are related to what the person search for on Google.
Will AmaSenseAds be related to your site´s content? I think that how successful this program will be for you and your site is related to how much customization you can do with it. If you can show only amazon ads that you really think is related to your content and that you think are very interesting, then you can probably sell them too.
Take a look for yourself at AmaSenseAds.