NXTPass is the next evolution in login pages. It employs a "Two Factor Authentication" API, a security system that requires a user to know a secret password and HAVE a secret password by sending an SMS or voice call to a cell phone with a separate one time use password.
We don't use any tokens or any hardware at all. All of our authentication is through SMS messages or voice calls. There's no easier way to get two factor authentication working in your own software than to use NXTPass.