I recently played "Battle for Minas Tirith", a map which has overlapping positive and negative bonuses, so that you gain production from certain territories, but only if you hold another particular territory. If you lose the "controlling" territory, those bonuses become liabilities for you, instead, subtracting from your production.
Are there any other maps which use this kind of trick in clever or interesting ways? It seems like a great technique to explore some more, but I haven't seen it in any other maps.
(Can you think of any other clever uses of negative bonuses?)
Once you level up you can start to change the bonus values in maps with only positive bonuses, some maps have super-bonuses that would allow you to create and customise the effect your looking for yourself.