Have you seen any CABLE measurement tests?

For RLC measurements, see Audioholics, esp. the cable faceoffs listed on this page:

http://www.audioholics.com/techtips/audioprinciples/index.php

"Straight wire without gain" is an ideal, not a real-world phenomenon. All wire will have some tiny effect on frequency response, most commonly a little roll-off in the top octave. And when I say a little, I mean generally well below what humans can detect. There are exceptions, and it's certainly possible to intentionally make a cable with really bad FR. But for most speaker-amp combinations, any cable with reasonably low resistance (meaning reasonably thick) will provide audibly flat frequency response.

Which is why cable purveyors don't publish FR plots--because they'd show something the purveyors don't want you to know.

I have personally measured all of my cables. Most of my interconnects are about a meter. My speaker cables are closer to three meters.

And the results are? ... Viridian?

Cable measurements would spell the death of cable mfgs.

measurements do not necessarily correlate to observed sound

Depends what you mean by "observed sound." Our everyday observations of sound are heavily influenced by non-sonic factors--setting, mood, prior opinions about the performers/equipment, etc. Your brain is wired to synthesize information from all your senses, plus stored memories, and that's what it does. Obviously, measurements of sound aren't going to tell you anything about all the non-sonic things that are part of your mental mix when you're listening to something.

But if we isolate our hearing perception from all that non-sonic stuff--by listening without knowing what we're listening to--there is a high degree of correlation between certain measurements and our perceptions. See, for example, the work that Floyd Toole and Sean Olive have done on speaker preferences. A good basic summary is contained here:

http://www.harman.com/about_harman/technology_leadership.aspx

See also Earl Geddes's work in progress here:

http://www.gedlee.com/