I have suggested this one before, but breaking up Europe into the drainage basins of the various rivers and grouping these by which sea they empty into gives a "natural" grouping of European countries and regions. You can see a lot of historical political units in this map:

(http://en.wikipedia.org/wiki/Water_divide)

Examples: the Ostsee basin is the Hansa you're talking about now. Donau is the Austro-Hungarian Empire. You can see the contour of Switzerland at the south end of the Rhine Basin. The border between Castilla and Aragon, between the French speaking and the Germanic regions are visible, and so on...

We have met the enemy, and he is us — Pogo