I would like to share something with you that is simply unbelievable. I optimized my client’s site in a small way that led to dramatic increase in traffic. It was up by 200%. The site already had a number of backlinks and was optimized previously. It attracted about 22000 visitors a day. I merely added title tags for links, made changes to URL and used PHP as opposed to keyword/keyword.php. I also replaced a few keywords as far as URL rewriting was concerned. I think search engines dislike deep looking paths despite them being linked from the front page.