If you have a good reason to find out what someone is doing on a computer that you own, there are a variety of methods. First, you can get software that will track their activities, but that can be easily noticed, and has the possibility of crashing at some point. Another option is to use a hardware keylogger, which intercepts keystrokes as they’re being delivered to the computer, and records them. This is more reliable and less likely to be detected, but only gives you text. However, this VideoGhost is a video logger, which essentially works the same way as a keylogger, but captures screenshots instead.
This device is pretty ingenious, as it simply connects to the end of your monitor and snaps a screenshot every few seconds. The only thing that gives it away is the USB cable that also needs plugged in. The images are then stored on the internal 2GB flash drive. At any time, you can flip a switch on the plug, and your computer will see it as a flash drive, where you can access the files. The device comes in VGA, DVI and HDMI flavors. Each will set you back $200. You’ll probably have to have a really good reason to drop that much cash, simply to spy on someone.