USB Blocker Freeware and Commercial - NetWrix Corporation: "The freeware NetWrix USB Blocker enforces centralized access control to prevent unauthorized use of removable media that connects to computer USB ports, for example, memory sticks, removable hard disks, iPods, and more. USB port access control is a very important aspect of your endpoint security, no matter how good your antivirus and firewall are. The USB device lockdown protects your network against malware and prevents theft of sensitive corporate data.
Unlike other solutions, it requires no deployment on client computers and relies only on built-in Group Policy mechanisms. Another advantage of the tool is simplicity, only a couple of mouse clicks to get the work done. And the most exciting: the software is completely free of charge."