[temugen]

And if you can actually input data using the protocol, you can take some standard packets and tweak a byte/short/long at a time and see what changes.

Reversing USB is the same as any protocol on top of TCP is the same as any other protocol, just with different tools.

I wish there were an open source hex editor like Hex Workshop for Windows - one of the features I loved was tagging a section of bytes with comments, and being able to use those same tags across multiple data dumps.

[opello]

Particularly handy for USB on Linux is the 'usbmon' module. Which when used with a kernel that has debugfs support, you can mount debugfs and use a new enough Wireshark to monitor the USB traffic.

http://wiki.wireshark.org/CaptureSetup/USB

[hoggle]

You could write your own by extending OSS like hexdump or hexcurse or any other hex editor. It shouldn't be to big a deal to add that functionality. It's just beautiful what you can do with open source code! Don't forget to share.