Have you seen turkey tracks? Here's one example:
http://www.quiltingboard.com/t-1753-1.htm
Looks like you make the "turkey track" then hide the thread in the sandwich and don't cut it. Just move over to make the next track. You'd just have to be careful that your thread didn't show through to the top of the fabric. You could probably do the same concept with a French knot or just a regular knot. I've never tried it, but I think it looks neat on the quilt.