Cion Systems, a US-based IAM (Identity and Access Management) vendor, recently released a free service that allows Windows users to implement two-factor authentication. It works only for Windows and supports either a PIN code sent via SMS (not available in all countries) or a standard USB storage key as the second factor. Thus, users can increase the security of their Windows devices in a simple and efficient manner, without the need of paying for a service or purchasing specialized hardware.
Their free service is based on the same technology Cion Systems is using for their enterprise self-service and multi-factor authentication solutions and services, which, e.g., also support password synchronization with Microsoft Office 365.
While such a service is not unique, it is a convenient approach for Windows users for increasing the security of their systems that still commonly are only protected via username and password.