This has been used many times already around the nets, but:
http://en.wikipedia.org/wiki/Nineteen_Eighty-Four
I dunno, really. I try not to worry too much about the possibilities and whatever the realities may be in this day and age. I still try to limit how much personal information I let slip out. If I were a really good analyst of computer and internet systems, along with the security aspects (however many there are), I might have a better idea of how many holes my computer has open to the agencies.
Wasn't more than a couple of months ago, though, that China hacked the Medicare databases here in Iowa. Information of about 80,000 beneficiaries is now in their hands. What they intend on doing with it is anyone's guess. I'm actually more concerned about how well our government can protect the information they keep than what they can "take" from us.
I'll have to cite some sources on the Medicare hacking a bit later. We're about to partake of some fine peasant food.