KeyLemon adds an extra layer of security to your computer log-in process by making your Webcam do all the heavy lifting. Instead of typing your password, KeyLemon 2.2 associates your face with your profile, and then regularly checks to make sure that the person sitting in front of the computer matches the image attached to that profile. If it doesn't think they match, the computer takes a photo via the Webcam and then automatically goes to hibernate.

The latest version of KeyLemon introduces a Firefox plug-in called LemonFox that lets users log in to three social-networking services using their Webcam.

Once installed, the program's Wizard will walk you through creating a profile of your face, and link it to your computer's log-in. By default, KeyLemon will check the Webcam every 10 seconds to make sure you're you, although that can be changed in the Control Center's LemonScreen tab. Also, KeyLemon conveniently includes a text bypass for your log-in. This is important because, occasionally, KeyLemon won't be able to recognize you.

The problem is rare, but I found it occurs in two situations. In bright-light settings where the details of your face get washed out, KeyLemon struggles and often fails to recognize your face. There was also occasional failure on laptops resuming from a closed-lid hibernation. One big bug was on laptops jumping from a dock to an undocked state, where the program would freeze the entire operating system and require a reboot. Generally, though, KeyLemon worked more than 90 percent of the time over several days of testing.

KeyLemon's setup wizard. (Credit: Screenshot by Seth Rosenblatt/CNET)

In the Control Center under the LemonScreen and LemonLogin tabs, you'll find a decent array of settings to tweak. These include being able to toggle on and off the log-in feature, configuring the program to run at start-up, program logging, reshooting your profile pic, and creating your own skins.

The Firefox plug-in LemonFox can be used to log you in to your Facebook, LinkedIn, or Twitter accounts. Just like the main program, LemonFox opens to a tutorial to get you started, and it uses the Webcam to prevent unauthorized access--at least on the computer with KeyLemon installed. It's a good idea to start with the social-networking services, but what I'd really like to see is integration with the Firefox password manager and support in other browsers.

Overall, though, it seems like a solid software tool for adding an extra layer of security to your computer for a reasonable price. The trial limits you to 30 uses, but has no major feature restrictions. A one-year license retails for $19.95, and it's compatible with XP, Vista, and Windows 7.