Windows 8 has an interesting way to unlock your device called Picture Password. Instead of typing regular passwords and pin numbers, picture passwords will allow you to unlock your PC in simple and secure manner.
This is how Picture Password works,
At its core, your picture password is comprised of two complimentary parts. There is a picture from your picture collection and a set of gestures that you draw upon it. Instead of having you pick from a canned set of Microsoft images, you provide the picture, because it increases both the security and the memorability of the password. You get to decide the content of the picture and the portions that are important to you. Plus, you get to see a picture that is important to you just like many people do on their phone lock screen.
Now, Microsoft is trying to patent this feature and below is the abstract of the patent.
PICTURE GESTURE AUTHENTICATION
In one embodiment, a picture signature password system may use a picture signature password to determine access to a computing device or service. A display screen 172 may display a personalized digital image 310. A user input device 160 may receive a user drawing set executed by a user over the personalized digital image 310. A processor 120 may authenticate access to the user session if the user drawing set matches a library drawing set associated with the user.