Name pretty much says it all, i think. How about a two-part map detailing a before and after scene? This can be a regions' political borders in two different times, or a castle during its prime and now, or anything else you can think of.
My Battlemaps Gallery http://www.cartographersguild.com/al...p?albumid=3407
Sounds good, but we'd almost need extra time as it's basically two maps.
It would be fun to see the different directions people would run with this one.
You could go with - rather than before and after some particular event - simply past and present versions of something. For a time-hopping adventure: London then vs London now. Or the Pyramids when they were originally constructed by the aliens vs the ruins the are now. Speculate on the world when the oil runs out - what will become of all the freeways and overpasses?