When I was at the Dallas quilt show, I saw a demonstration on something called Ruler Magic. It is something like Elmer's glue or rubber cement. You spread it on the back of a ruler, and let it dry...it dries clear. Then when you put your ruler on the fabric, it sort of sticks, so the ruler simply can't move. You sort of peel your fabric off after you cut it, but none of the Ruler Magic seems to stick to the fabric.
I didn't get anywhere when I googled it, so I can't give you a website or anything. The lady at the booth said she had invented it and I think she was just getting started with it. There is a phone number to call for reorders on the bottle. PM me if you would like that number, as it is probably wrong to put it here.
I did buy some and it is pretty neat stuff. One application seems to last a very long time, but if it loses its ability to stick, it says just to reapply it.
Dina