In all our discussions of privacy and security, we tend to focus on the technology and not pay attention to the weakest leak in the chain, the user. I just got a real good example. I went to a second hand store today and they had a bunch of recently arrived cell phones, all for the same low price. I took the iPhone 3g. When I got it home, I charged it and was greeted by a selfie of the the former owner when I turned it on. If I let in on my wifi network, I could have gotten into his gmail account without even trying. I did the responsible thing and erased everything but it could have easily been bought by someone less responsible. Until the basics of online privacy and security are widely understood, technology is going to continue to melt away in the hands of a careless user.
Along the same lines just go to a coffee shop (starbucks as example) and watch countless folks using their laptops wide open and "snatchable" in every sense of the word. They know better if you ask them, but they do it every single day even after they get burned a few times. There are times I really feel like formatting a few C drives, but I never do.
I've bought dead computers on ebay to repair that still have the original owners hard drive in them with all their personal data, lucky for them I am not malicious.
I picked up a PC at a yard sale. On it was one of those home lawyer programs, along with the guys last will. Of all the things to forget and leave on an old PC.