A big contributor to Amazon's success is its ability to allow consumers to share their reviews.
This article in Harvard Business Review argues that companies can build trust among consumers by making the shopping process simple for consumers and includes many examples of facilitating consumers to help other consumers.
http://hbr.org/2012/05/to-keep-your-customers-keep-it-simple/ar/3"Disney has done an outstanding job in this regard with its Walt Disney World Moms Panel. A selected group of Disney World veteran moms answer questions from consumers who are planning Disney vacations. In one recent case, a consumer asked about good viewing places for the parade; she had two children who wouldn’t be able to stand the whole time. She got perfectly tailored advice from Jackie S. With 25 Disney World trips under her belt, Jackie has the experience to make her information credible. Consumers can get a further sense of her reliability by reviewing her profile on the Disney World website and reading about her family, her hometown, and even how she met her husband. Such details matter: They help consumers assess the trustworthiness of the advice they’re getting and allow them to judge how well that advice applies to their own situations.
The lesson for marketers: Build cadres of trustworthy advisers rather than simply developing recommenders who will push the brand. Then aggregate their advice and make it easy for consumers to discover and use it, as J.C. Penney—whose haul videos get hundreds of thousands of views—so successfully does. "