Story: Built a custom BH eCommerce site for a particular niche. Was having trouble ranking it for seemingly easy keywords. One day i noticed that my rankings jumped (went from page 4 to page 1/page 2.) Went to the site to add some more content and discovered it was erroring out with an http 500. Fix the error and suddenly my ranks went down again. It made me investigate. Discovered that I had forgotten to redirect www to the non www version of the domain name. Doh! That counts as duplicate content for Google. I was getting penalized. I checked the index and sure enough, both the non www and www versions were indexed. Quickly 301ed www to non www and problem solved. Moral of the Story: Look for stupid mistakes like that, and ensure that your content is unique. Make sure your www is properly redirected to non www or the other way around.