Not scaled movement, but there was research done in the 90s about having the computer subtly "distort" (I can't remember how it was really done) things being displayed to in effect make you walk in a curve to keep you away from walls (I think it was similar to how you can attempt to walk a straight line in a forest - and without a compass, actually find yourself walking in an orthogonal direction compared to where you started - simply due to ground level differences, motion cues, etc). I'm not sure how well it worked, but it was a workable system.
There's also the more expensive idea of an "infinite 2D treadmill" - which was first implemented by a guy named Rudy Darken; iirc, he did it for the "dismounted soldier" VR/AR training project for DARPA:
'redirected walking'. This has been used in practice by some of the big VR applications and in research since them. As I understand it, the problem is that it doesn't solve the 'small living room' effect because you can only distort by a few degrees and this produces a circle of like 15 meters - so works in a sort of warehouse setting but not in normal buildings.
There's also the more expensive idea of an "infinite 2D treadmill" - which was first implemented by a guy named Rudy Darken; iirc, he did it for the "dismounted soldier" VR/AR training project for DARPA:
http://dl.acm.org/citation.cfm?id=1246853