Years ago, I saw a system that Carol Bryer Fallert used and I took her idea and made a system of my own. Here's a link to Carol's site.
I use a portable photography stand like this one:
Most of the time, I just drape the quilt over the bar. If it doesn't stay, I use a small clamp. I try not to use the clamp because its easier to move the quilt with out it. As I work different part of the quilt, I can easily re-drape the quilt to lift the part I am not working on.
Doing this is really a life saver in terms of lifting the weight... it makes it SO much easier to free motion quilt.
You wouldn't think that lifting your quilt just a few inches off the table could really help much, but it does. Saves lots of stress on your arms pushing that weight around, and actually allows better stitches because the quilt will move easier.
Here's a full image of this quilt... taken before I started quilting. The quilt is a redo of a quilt that was made in 1890s.