Why not have worlds that are adjacent in 3-space surrounded by environment maps
that show a rsndering of neighboring worlds? That way, you look around you at
3-D buildings surrounded by "wallpaper" that shows the next block in a city,
and so forth. Kind of like a museum diorama. Of course there's going to be
a bit of delay, especially when you look at stuff that has propagated across
several worlds. This means the speed of light is equal to the diameter of a
world divided by the net lag.
Such an approach becomes profitable when sending the pixels of a
texture map requires less bandwidth than sending the actual VRML.
QTVR probably wouldn't be the best for this, since cylindrical worlds
don't tesselate well. A texture-mapped box would do just as well. And when
you walk through the wall, you load the next world over.
Pete