Maybe this one shown at Nancy's Notions works because it's got two separate surfaces that are anti-skid, and the angle thing may help too. I may have to look at trying one of them.
I've never had anything that stopped my foot pedal from migrating away as I sew, and it sits on carpet. I've tried just about everything and the best I can do is slow the migration by using a peel and stick set of little teeth meant to keep furniture from digging in to carpet.