Amazon apparently launched Omakase recently. It's an adsense-like program that shows the user products based not only on the page-content (ala adsense) but also based on the user's preferences.
While this doesn't help sell services, it's an amazing way to sell products. Amazon knows products and it knows consumers. I know often-times on the amazon page, the products shown to you are in fact items from your own wishlist - that's probably because people are more likely to buy products for which they've already expressed interest.
Now, if I'm browsing around the web, amazon already knows what I've got in my wishlist, what I've been looking at on amazon, what "similar" people have been looking at, what they've bought, and how the site I'm looking at now might influence what I want to buy.
That's an aweful lot of information to put together. Although the current algorithms may not exploit all of this information my guess is that, as they iterate on Omakase, the recommendations will only get better.
Now if only you could ASIN-ize services...