What happens to all that personal data that gets collected?

Yesterday on +TWiT +Leo Laporte and +John C. Dvorak asked what companies are doing with all the personal dat they collect.  Well here is part of that answer -

Software that tracks people on social media created by defence firm

Exclusive: Raytheon's Riot program mines social network data like a 'Google for spies', drawing ire from civil rights groups

I'm not saying that Google / Facebook et.al are actually spying on their users, but we all know that there are a lot of companies out there that are compiling data and selling it and that data could be used for things such as this.