I think that it might be interesting to have an almost "barter"-esque table. Where I could maybe rent out units like mercenaries (appears in a buyer's province and reutrns to me after 3 months or some such). Agreements on moving through each other's terrain, mutual attacking, maybe even allowing my opponent to take resources from my provinces w/ a fort. Or gem donation, item donation, and gold donation. I think that that would cover most all the possibilities. And maybe if I give away some armies and am conquered before their return they become real mercenaries.
I know that this is probably too much and a small thing compared to others, but it would be sorta nice.
