The US National Security Agency was granted a patent on September 20, 2005 for new technology that allows them to identify the physical location of any web surfer.
"If someone's engaged in a dialogue or frequenting a 'bad' Web site, the NSA might want to know where they are. It wouldn't give them precision, but it would give them a clue that they could use to narrow down the location with other intelligence methods," said a researcher.
The NSA's stated uses for the technology included "effectiveness of advertising across geographic regions." Source