I successfully sell using Amazon Affiliates on a number of my sites, if its done right and offers value to your readers then it is definitely worthwhile..also make sure the product that you are recommending actually does what it claims to do as recommending crap just for the commission will drive your visitors away.
It is just a standard affiliate product promotion, you promote a product and when the buyer clicks through your link to buy the product then you are given a certain % commission depending on the product.