USB Malware Threats

Have you ever experienced problems which is almost a nightmare to monitor and manage effectively the use of USB drives or removable media in your corporate network domain? I find this to be an issue within my network. The increase in the use of removable devices is posing a real threat to internal data security. Whilst my AV end point product effectively detects, alerts and fixes malware, I dont have a way of blocking off the use of USB devices as a proactive control measure. What is the best tool recommended for use in this scenario and is there are practical best practise for this?