A month ago, I wrote about a company called TwittAd that lets you auction off ads on your Twitter page. Now, the company is sponsoring WhatsYourTweetWorth?, a vanity site where you enter your Twitter name, and it tells you how much your Tweets are worth based on how many followers you have. (Try it later, the site is down—probably being overwhelmed by people who are already Twittering about it). Before it went down, it said that TechCrunch, which has 26,361 followers, is worth $503 per month. Except that, it isn’t.