[MikeDubreuil]

This will not work and here's why...

If you put a hamster into a globe he's surrounded by air. The air has zero effect on the physics of the globe rolling because the air is both inside and outside of the globe. The only mass inside the globe is the hamster. The hamster is able to make the ball move by applying force against the wall of the globe. Since there is no other mass in the globe there's nothing from stoping it from moving. (of course this wouldn't work for any other shaped object, say a square) Basicly, the hamster is changing the center of gravity of the sphere causing it to move in an attempt to bring the center of gravity to the middle of the sphere again.

If you filled a globe with water and inserted a fish into it the fish would not be able to significantly change the center of gravity. The fish would weigh so little compared to the weight of the water that it just wouldn't work.

EDIT: Sorry, after re-reading I realized you already knew it was impossible.