This is a great video showing not only what kinds of hacks people can do, but actually covering the process. If you're writing detective fiction or anything involving extracting private information I think this video is a must watch.
http://videosift.com/video/Never-Dare-A-Hacker-To-Hack-You
http://videosift.com/video/Never-Dare-A-Hacker-To-Hack-You