There are a number of USB devices that only use a USB port for power,
reading lights, fans etc, so they stay on as long as the port is powered on.
Some USB Hubs support turning on/off the power to individual ports.
It is part of the USB 2.0 spec.
Example : Hawking UH214 USB 2.0 4 port hub
A utility that can turn a USB port's power on/off is ideal.
MS has the devcon.exe command line utility that can identify ports/devices
including HID and USB
http://support.microsoft.com/kb/311272
Linux C code that can turn on/off the power to a USB port.
http://www.gniibe.org/ac-power-by-usb/ac-power-control.html
Any ideas ?