The ability to create custom caravan templates or packages, that you still have to manually send but can do so with much fewer clicks. When you create caravan orders, you have an option to save as a tmeplate/package. Next time you go to trade orders, you can choose one of your packages from a drop down and then just specify who to send to.
Let me provide some examples:
New Player package: 5,000 of the 5 basic resources.
Siege support: 50,000 of the 5 basic resources
Shared resource supply: A rearranged number between players to regularly split the yield of a resource node (I had an arterium one at 60 Arterium a week.
Troop production resources: 10,000 sword, 5,000 beer, 5,000 mail, and 5,000 plate for dwarvish infantry.