DebJ,
I just saw a thing in my McCall's magazine this morning about a fabric mover, not sure if it is what you saw at the quilt show or not, but they are called Fab-U-Motion. On ball bearings to move the project in all directions. The product review says it fits "most" machines and that for most machines you can get a stitch regulator.
http://www.husqvarnaviking.com/us/7610.htm
That's the link, I'm checking it out for cost and such. It will help my arthritis a lot if it's affordable.
Hugs,
Sharon