Is there a summary in Civ5 of all currently active (trade) agreements with all other civs?
There is only the deal history you already found (Diplomacy -> Diplomacy Overview -> Deal history). The history differentiates between active and older deals, so you only have to check the list of active agreements.
Lets hope they provide some better overview with a future patch.
You can also click "declare war" in the diplomacy screen and the game will present you with a list of current deals and trade arrangements. Just don't click "yes" after that unless you want to.