Maybe Mark Zuckerberg is right about this end-of-privacy business. A Wall Street Journal investigation (stories here and here) makes clear that whatever you do online, you can rest assured that some advertiser somewhere knows about it. It's not that tracking cookies exist that's so troubling, it's that there's so many of them. The top 50 websites installed an average of 64 pieces of tracking technology onto visitors' computers, and a dozen websites (including Dictionary.com and MSN.com) installed more than 100.
The cookies are way more powerful than those of a few years back and can pinpoint your "location, income, shopping interests and even medical conditions," writes the Journal. Try to delete them and they "respawn." One small bright spot: They usually don't have your name, only your age and gender. The selling of such user profiles (on new exchanges similar to stock markets) is now one of the fastest-growing businesses on the Internet.