About software that tracks you through your use of social media:

http://www.guardian.co.uk/world/2013/feb/10/software-tracks-social-media-defence?CMP=twt_gu

This paragraph was telling:

"But the Massachusetts-based company has acknowledged the technology was shared with US government and industry as part of a joint research and development effort, in 2010, to help build a national security system capable of analysing "trillions of entities" from cyberspace."