Extortion used to be such hard work. Blackmailers would go to great lengths to dig up someone's secrets that they could threaten to make public. These days, such compromising information is already nearly public. Armchair extortionists need little more than a keyboard and some hacking skills to take people's private data hostage. Think of the most sensitive information that exists about you in digital form -- from electronic medical records to Internet browsing histories -- and it's easy to see how high the stakes are when those records are held for ransom. Here are some examples.