Amazon has probably been the most successful company to start a business selling goods form the Internet, books at first, followed by CDs, DVDs, and now almost everything (from gardening tools to hard-to-find food ingredients). As you certainly know, its US site (as there are other localized and regional versions) is at:

      http://www.amazon.com
    

One of the features pioneered by Amazon—which quickly became popular in travel sites like TripAdvisor—was users ratings and comments. Any user, even without having bought a book, which at times caused some odd situations when comments started surfacing before a book was available, could give a book a 1-to-5-stars rating, which is clearly on display and affects the book's popularity and its display order when browsing a topic or running a search.

Users could also insert detailed comments, which (a later addition) could be approved or disapproved by other users. Amazon was also first to give out almost real-time sales figures, with a sales rank number updated hourly. But that's beyond our topic, even if quite relevant. On the community site, Amazon enables user to create wish lists and featured lists for various topics, and was the first (and possibly the only) to fully integrate third-party resellers in their system. It was one of the first to compensate for referrals using links leading to a sale by a new user. Other Amazon efforts, such as tagging books and letting authors blog on the site have had a more modest success, if any.

In case you are interested, my Amazon profile and empty blog is at:

      http://www.amazon.com/gp/pdp/profile/A335B2K2GCRABH
    

Today Amazon is a popular online warehouse, but on the technology side, it offers intriguing hosting, storage, and computing services, one of the biggest web services architectures, and is the owner of Alexa, a powerful web search and analysis site:

      http://www.alexa.com