Did you know you can use a USB stick to secure your computer when you're in public?

Obviously, it can't stop someone picking up your machine and walking away with it (unless the USB stick is made of lead), but it can stop prying eyes from having a quick look at your personal documents while you're stood up ordering your next iced frappe-latte-mocha-chino.

Sounds great, but how can you make this magic happen? It's all thanks to a wonderful little app called Predator.

The Predator app lets you lock and unlock your PC by removing or inserting a USB flash drive. You can use any USB stick, so you don't have to remember to take the same one with you every time you leave the house. As long as you have a USB stick on your person, it will work.

The app works by generating a security code and placing it on the USB stick. Every few seconds, it checks to see whether the code -- and by extension, the stick -- is still present.

If it's not present, the app prompts you for a password. Entering an incorrect password, or no password for 20 seconds, will cause Predator to deny access to the machine and potentially sound an alarm, depending on your settings.

When the USB stick is removed, both the keyboard and mouse are disabled, and the screen darkens.

Predator will also let you specify certain times of day when different people can use your machine, and will even give them all unique USB codes on their own sticks to let them log in. This is perfect for managing how long kids can spend in front of a computer.

Best of all, if you have Predator installed on several computers (e.g. at home and in the office), you only need to have one USB stick. All the machines connect to your account will recognize it.

Oh, and don't worry about losing the stick. You can set a master password to override the software.

A home license costs a one-time fee of $10.

Have you used Predator? Share your experiences in the comments below.

Image Credit: Studio ART via Shutterstock