Go here, to Take the High Ground, and read about this really cool project.
Essentially, the fellow in charge of that blog is trying to make a complete game that you can carry about in a reasonably small box. His original goal was a cigar box, but that proved a bit too small. Now he is scaling it for one of those plastic art supply boxes.
I am thinking I might be able to manage something a little larger for 6mm (he is using 2mm scale). The rules are really simple, as well. Which we like.