Tetrahedron walker could be used anywhere.

I was reading about this thing in a magazine a while ago its a really great concept. All that it does is move its centre of gravity past its base which makes it flip over, to do this it has telescopic axes (of which there are 6) which means it can move in any direction. There are even plans to build ones with 10 sides, which theoretically will be able to also link together to form a variety of different structures.
Watch the video i have provided the link to.

ants.gsfc.nasa.gov...

That's really fascinating, I'll have to think about this for a bit, I've not seen anything quite like it.

Of course, the obvious question is that of energy, where it would get it's power from. You could put batteries inside the tubes, really the only place FOR them, but I don't like the idea of constantly crashing your energy sources to simply move.

It could use CoolChips to draw energy from the ambient temperature. Only would work if they get it to use energy really effiently.