Amazon Associates and Amazon Fulfillment Web Service (FWS): Anyone who has clicked through a site to order something from Amazon has used Amazon Associates: It's the service that lets you sell Amazon stuff from your Web site. You get a percentage -- a referral fee -- for each sale. There is not much more to be said about Amazon Associates.
A more interesting Amazon e-commerce service, however, is a remarkable kind of inverse of Amazon Associates: Amazon Fulfillment Web Service. With FWS, instead of your selling Amazon stuff, Amazon sells your stuff. Not only that, but Amazon will also warehouse, package, and ship your stuff.
FWS is actually two Web services: inbound and outbound. You use the inbound system to inform Amazon of incoming shipments bound to their warehouse. When a customer orders one of your products, you use the outbound service to inform Amazon of the sale. Based on the details of the order, Amazon packages and ships the product, and even provides tracking information that you and your customer can use to monitor the shipment's status.
Of course, there are warehousing and handling fees involved, but it's a compelling model. A small company, unable to afford warehousing and shipping costs, can "virtualize" those components with Amazon FWS, until that company is large enough to provide them for itself. And any developer interested in exploring the mechanics of the inbound and outbound services will be happy to discover that Amazon has provided "scratchpad" applications -- tools that let you exercise simulations of the services.
Mechanical Turk: Amazon's Mechanical Turk is a peculiar service. (It is difficult to categorize; I have listed it with the other e-commerce services.) Its name comes from the famous 18th-century robotic chess player invented by Wolfgang von Kempelen. The robot, however, was no robot; inside the machine was a human chess player who operated the mechanism, unbeknownst to the human opponent. The idea of Mechanical Turk, then, is an automated front end, behind whose machinery hides a human.
Only, in this case, it's not just one human; there're lots. Whereas EC2 provides an elastic cloud of computers, Mechanical Turk provides an elastic cloud of humans. But this analogy goes only so far; the computers in EC2 are virtual, the humans of Mechanical Turk are not.
Here's how it works. Suppose you have a big pile of identical tasks that must be performed by humans. Perhaps you have a large quantity of text files that must be translated from one language to another. In the world of Mechanical Turk, you are a requester; you submit your tasks to the Mechanical Turk service, which places them on a kind of global bulletin board. Using that same service, workers log onto this bulletin board, select tasks, perform them, and post the results back to the service. Later you return to the Mechanical Turk, review the posted results, select those that are acceptable, and release funds to pay the workers. In short, the Mechanical Turk service is a middleman between employers and employees.
When I first read Mechanical Turk's description, I thought it was a great idea. It may yet be, but if my perusal of the tasks that are available is any indication, this is not a way to make any appreciable amount of money. Most of the HITS ("Human Intelligence Task," referring to a unit of work) posted paid mere pennies, and reading some of the descriptions gave me the uneasy feeling that workers would be used as human spam-bots.
It is possible that, in the future, Mechanical Turk will become a marketplace of decent work for reasonable money. For now, though, I am confident that I can make more money in less time -- and do more good -- by mowing the old lady's lawn next door.