I can't find solid analysis of Amazon's rating system, but neither YouTube nor Netflix are bimodal: * YouTube is all 5 stars (http://youtube-global.blogspot.co

I can't find solid analysis of Amazon's rating system, but neither YouTube nor Netflix are bimodal: * YouTube is all 5 stars (http://youtube-global.blogspot.com/2009/09/five-stars-dominate-ratings.html http://youtube-global.blogspot.com/2009/09/five-stars-domina...) * Netflix: 3, 4, and 5 dominate (http://www.timelydevelopment.com/demos/NetflixPrize.aspx http://www.timelydevelopment.com/demos/NetflixPrize.aspx)