In an attempt to simulate the NSA's capability, Ars tracks its own editor for 11 days.
“Facebook knows if you hit any page that has a Like button it,” he said. “Same with TweetThis, unless the site goes out of the way to mask them, then these are specifically reporting them to social networks. This is why NSA loves it, is because they can go along for the ride.
“One thing that we know that the NSA does on their non-US wiretaps is bind usernames to cookies so if you see a request for LinkedIn or YouTube or Yahoo, these are all sites that have user ID in the clear, all you need to do is see a request, and say I don't know who this is or I know who this is, but then you look at the HTML body and look for the username. This is why the NSA went after Google ad networks, include user identification [broadcast] in the clear: ‘I am person X at this location.’
Despite the vast amount of data, it's just as easy to store as it is to interpret. “It works out to only a few kilobytes per person for everyone on the planet,” Weaver added. In other words, if I had the access, it'd cost just a few thousand dollars to have enough consumer-grade storage to keep data on everyone in the United States. It would comfortably fit on my desk.
Via Gust MEES