Interesting list.<p>But, if you summed the market caps of all these companies, what would you get?<p>My guess is $2-5 billion.<p>Now Google alone is worth ~$200B.<p>I agree that you can start a really successful Internet company in NYC. I'd say any city in the U.S. would do. However, if you have some pathological urge to build a gigantic Internet company, you absolutely <i>need</i> to be in Silicon Valley.