A couple of years ago, when I worked for a search engine marketing and analytics company, I was speaking to a potential client about his paid search engine marketing efforts. He was explaining to me how excited he was that he had just increased the traffic to his e-commerce web site by about 10,000 visitors. After listening to how he used Google AdWords and Yahoo to improve his ad rankings, I dropped a bomb on him. I explained how great it was that he was getting more traffic, but I finally asked him.... "So what's your conversion percentage for those keywords you bought?" He said, "My what?" I said, " Do you know which keywords work well and which ones don't ?" There was a pause.....he didn't know the answer. I then asked, "How do you know if the money you're spending with Google and Yahoo isn't being wasted?" He said, "Because I'm getting a lot more traffic." I then told him, "Do you realize that you can b...