Stickonspy sells die-cut stickers that go around your laptop's webcam to remind yourself -- and others -- that spooks from western governments have made a practice of using spyware that allows them to covertly switch on laptop and mobile phone cameras and microphones to spy on their owners. $3 for one, $10 for 6. We used to sell a variation on these in the old Boing Boing Bazaar. Just remember to trim away enough of the sticker that you can see if the webcam light is lit, which will prevent some of the less-subtle attacks, and also inadvertent embarrassment.
Stickonspy (Thanks, Bradley!)