[ljf]

Amazon plays off its suggestions of what else to buy, that data is from the network, not your personal network, but the data is only valuable once you have enough users, or else the data is too spiky.

These suggestions to just throw one or two more targeted items into your basket is where they really excelled.

[FaceKicker]

Do people really use these suggestions though? I don't think I've ever used them personally (maybe once?), but maybe others do. And even if people use them very frequently, I still don't think that would make the usefulness of Amazon grow as a "square" of the number of users as the article implies.

[ljf]

Yes, I've used them many time, and I know my (non technical) girlfriend does too.

I've found similar novels that I've liked through the suggestions, bands I've enjoyed and recently when buying the 'Lean Startup' I ended up buying 2 of the suggested books.

Many time I end up not buying the item I originally went there for, instead buying one of the suggestions, or the suggestions on a suggestion... depends how the reviews look.

As I see it Amazon were the first to really use this data successfully and meaningfully.

The other networks I guess would be the Amazon Wishlists which for a time were hugely popular. I still see wishlist links on personal and informational sites, as a way to give back to the site creator. That network is pretty powerful too!