That reminds me of the Total War games, which were awesome. Are you talking about a sort of campaign map within which you take over individual provinces? That would be totally awesome, to the max.
This could be done with flash or with image maps. Flash would load faster, but it'd look worse. Image maps might be a little harder to make, and they'd load slower, but they'd look a lot better. I could probably do this. I really enjoy making maps, and I think I could probably handle the code.