We all know the NSA collects meta data on US citizens.  This has been pooh poohed by much of the media, and Obama,  as unimportant.  However, meta data is incredibly useful to determining social networks. This means that if you know one individual, you can find the rest.  For example, this old blog post by Kieran Healy on Paul Revere demonstrates that if the British had known Paul Revere’s meta data, they would have been able to identify the rest of the “rebels”.  If the British crown had had meta data, they could have destroyed the nascent US rebellion before it became a new nation.

Bruce Schneier has also written extensively on the uses of meta data.  He views using meta data as putting the entire population under surveillance.

What do you know about meta data?