Now that I'm into writing reviews on amazon as part of my quest for a broader literary life, I was happy to read on the Creative Penn that those ratings and reviews make a difference in where a book shows up in the Recommended Lists on amazon. Lesser known authors can have their books materialize in these recommendations when they have a significant number of reviews, and all of a sudden they are a player. Joanna Penn of the Creative Penn relates her experience with her thriller Pentecost:
"Ratings and Reviews make a difference. Pentecost has 32 reviews as I am writing this with 4.5 star rating on Amazon.com. This is more than a whole lot of big name authors and clearly Amazon pays attention when readers are enthusiastic about a book."
So: Write amazon reviews and rate those books you read!