Companies exist solely to gather and de-anonimize this data to the fullest extent possible. As an example of what you can do, in Google Adwords, you can downloa

Companies exist solely to gather and de-anonimize this data to the fullest extent possible. As an example of what you can do, in Google Adwords, you can download multiple aggregated click/cost reports across many dimensions (age range, zip code etc), set up and solve a mixed integer linear programming problem, and get detailed information about every click. Not sure if Google ever caught on or cared enough to fuzz the data.