USB Sniffer for Windows 98/Windows 2000/Windows XP (1,959)
Allows you to sniff the traffic between a USB device and your (Windows) machine. From the webpage:
This source code has been inspired from a USB sniffer for Windows 98. This sniffer is based on the WDM architecture (Windows Driver Model), which supports the insertion of filter between device drivers. And the filter itself is a driver.