Flash-sale newcomer Fab.com in December 2011 rolled out an on-site social feed that allows shoppers to share their purchases and favorite products on the site and with friends. The feed, which shows visitors who is buying which products on the site, resembles the image-focused grid of Pinterest. Shoppers viewing the feed can designate particular items as their favorites or share products on social networks. So, if a shopper has signed in to the site with her Facebook account, and purchases the Yuba Infinity Scarf, for example, that purchase is then shared on Fab.com, as well as on her Facebook Timeline. This drives extensive peer-to-peer sharing of Fab.com's design-inspired products, says founder Jason Goldberg. Fab gets around 25% of its traffic from social networks.

• Date Launched:2011
• Unique Visitors:450000
• Web-based Sales:Order the Hot 100 issue