Advanced USB Port Monitor
Advanced USB Port Monitor is a USB Bus, USB Device and Protocol Analyzer. Advanced USB Port Monitor packs the robust functionality to capture, view and process USB traffic. It offers sophisticated viewing and intelligent searching to accurately and efficiently debug and test High (480Mbps), Full... The Advanced USB Port Monitor design enables users to use it with any USB device, extending beyond the lab environment to the personal workstations of USB developers and advanced USB device users. ... Most users - USB hardware and software developers, advanced users - will appreciate the value...
http://www.aggsoft.com/download/ausbmon20.exe - 3Mb - Download - Screenshot

RapidDriver
RapidDriver is intelligent tool for driver development, PC hardware analysis and debugging. RapidDriver allows you to start work with hardware after just a few clicks. Simply install your new hardware, create a new RapidDriver project, and then select your USB, PCI, ISA, or a parallel port... The Developer Edition of RapidDriver includes all the features of the Explorer, and additionally allows you to create and distribute your own applications incorporating integrated ISA/PCI/USB/LPT drivers to control your hardware.
http://www.entechtaiwan.com/files/rdeval.zip - 5Mb - Download - Screenshot

Eltima Serial Port Monitor
Serial Port Monitor is a professional application for RS232/422/485 COM ports monitoring. It monitors, displays, logs and analyzes all serial port activity in a system. It can effectively be used for monitoring serial data exchange between serial devices and any Windows application, debugging... Serial Port Monitor supports all COM-port types: standard on-board ports, extension board ports, SERIAL-via-USB adapters. ... Serial Port Monitor will automatically append all monitored data to a file in real-time.
http://www.mks.zp.ua/serial_port_monitor.exe - 3Mb - Download - Screenshot