We have recently completed interoperation testing between Radiator RADIUS server and the WiKID Enterprise RADIUS Server. WiKID is 2 Factor authentication system from WiKID Systems (http://www.wikidsystems.com/).
The WiKID Strong Authentication System is a patented dual-source, software-based two-factor authentication system designed to be less expensive and more extensible than hardware tokens.
It is available with both soft- and hardware tokens.
We have added a sample configuration system to the Radiator distribution showing how you can proxy a selected realm to WiKID, while authenticating other realms locally within Radiator (this is a common technique for migrating users from one token system to another).