Have you heard of a reverse-T-ring?

I'm wondering if theres a way to convert a Nikon mount lens to be a small refractor for imaging with a ccd.
So, I would need somthing that acted like the camera body, giving me a thread to use on the other side to mount a focuser or whatever.

I know this is the FILM forum, but this is the audience with the lens experience, so I thought you guys might know.

Thanks!

Sure, I have such a thing for my Olympus lenses. I would suspect it came from the CCD people, but I really am not sure.

Alex