Try this one for size: more than one map in play at once, where you can move forces between each other via a common border. E.G. Take the excellent existing maps for Great Britain, France, Italy (and of course the other Euro ones). If I'm playing a 4 player on each and I just happen to have judged Italy as a lost cause, I could pull my remaining men out of there and try to do something useful in France or GB instead? Likewise the opponents. What it might mean is that you think you've conquered one country but then 35 armies turn up from the other fronts and ruin your day. You'd get your territory bonuses from all maps collated and then carefully deploy them however you choose. This could bring about strategic withdrawals and a new level of play required, slughtly more complex but could be fun!
The maps would have to be defined as a set at the outset, and of course you'd need all players to be playing the same game type across all maps (or they'd be at a huge disadvantage). For ease of use we'd need a hyper link to flip about between the maps.
Think of it as a zoom function for the World maps Interested, or does it sound unworkable? Place your vote now!!