The argument of "useless knowledge" reminds me on arguments against taking maths and general+quantum physics courses at the university (compulsory basic courses at my alma mater). I never considered any knowledge (except communist ideology - compulsory then, too) useless. I like the idea of renaissance men - not too popular today, I know.

But speaking practically, I don't know how such a USB analyser works, never had any - I thought it connects to PC and outputs the "sniffed" datastream in some human readable form to the screen. But I see no real time action in this, if a human has to read the output - or am I completely wrong?
Well I can imagine a device in between a USB host and device, inserting and/or removing "features" from the datastream - that would require realtime operation, but I cannot imagine the purpose of such.
Can you please explain?

Jan Waclawek