Nice presentation from SecTor 2010 that explains how to use OTP and Radius to secure the network.

Radius can easily be integrated with PAM: SSH, sudo, su, openvpn, postgresql, …

I like the solution they offer to allow the users remotely access their desktop. FreeNX is tunneled through SSH (user authentication via OTP)  and offers X, VNC, RDP, desktop sharing  and session shadowing.

Video  Slides