This USB Kitty would last maybe one day in my house. Its infrared sensors alert you of intruders when you walk away from your computer, by shaking its head and making hideous meowing, hissing, and singing noises. It provides a whole lot of irritation for just $24. The sound is so incredibly annoying, I don't know that it would survive the first time I trigger it accidentally.

But if you're a cat person (unlike me) and can control yourself better, then you might think this is just the ticket to keep your computer from prying eyes.