Guide to social networked shopping

We try to list here the most important social networks for consummer products and shopping. Must be split by category if possible

Solutions

 * wists - social shopping
 * yelp - social reviews, may be useful as social service review

Related HowTos

 * Social networks (What free software is there for)
 * Blog links related social networks (What are the best)
 * Social networks for links (What are the main free and open)
 * Meet and interact with people (What are the social networks where you can)