Many computers sold these days come with web cameras built right in. You may never use it, but hackers can spy on you and record things going on inside your home and even use it to blackmail you. 
Watch Brian Mylar's ReportThe FBI recently arrested Luis Mijangos for hacking into more than 100 homes by turning on the webcams in their home computers. "In some cases, he was able to turn on the web cameras that were on people's computers and, just by dumb luck, happen to catch them walking naked across the room," said an unidentified spokesman for the FBI.
Then, in a "sextortion" plot, Mijangos emailed those people and threatened to release the video unless they made more sexual videos. He also posed as the victims' boyfriend, asking women to send sexually explicit photos and videos and he told the FBI he's part of a big hacking group. (more)
Tip: Cover the camera when not in use.
