Do you pay any attention to the reviews listed for each book or CD when you’re browsing through sites like Amazon or Ebay? I surely do. And it seems I’m not the only one: a research by Opinion Research Corporation revealed that 61 percent of respondents first check online reviews, blogs and other online customer feedback before they buy a new product. Most of them make use of search engines to find more information about a specific product. Half of the respondents need 4 to 7 customer reviews before purchasing an item. More than eight out of 10 said this kind of evaluations had at least some influence on their purchasing behaviour.
Reviews can have a big impact on brands, there is no doubt about that! 
Recently, more and more retailers allow SNS users to link their profiles to the web shops. In this way, peer pressure and the opinions of our friends will play a large role in our purchasing decisions. Moreover, this may mean that in the near future almost every online site will have its own social-networking component. Online shopping will no longer be an individualistic activity as customers will be able to share their online shopping experiences.
Sources:
http://blog.washingtonpost.com/posttech/2008/05/the_allthingssocial_craze.html
http://blog.washingtonpost.com/posttech/2008/07/peer_pressure_in_online_shoppi.html?nav=rss_blog
