I've just received this in a newsletter I subscribe to, so I haven't tried it. Has to be better than chemicals if it works though.
One of the most distressing things is to see dye run in a quilt. It can be rescued with a bit of patience and ... natural yoghurt. Take the yoghurt and rub it onto DRY quilt top, leaving sit for an hour or so. The longer ther run has been in the fabric the longer you need to let it sit. The yoghurt may chance colour as it removes the dye. When you think it's done the job, wash your quilt in tepid water.