Microsoft has kicked things off at its Computex keynote with a small demonstration of logging into Windows 10 with nothing more than a fingerprint scanning wearable (the Nymi Band). Stating that such support and functionality is already built into Cortana, it's yet another way to conveniently yet securely sign into your Microsoft account on your PC.
It's a neat concept and is part of Windows Hello Companion Device Framework that will enable third party companies to produce new hardware that can connect to Microsoft's own platform. You'll eventually no longer require your password to get into Windows 10. Just sign-in using Windows Hello or scanning your fingerprint on a connected wearable.