In 2372 the Council condemned the Klingon invasion of Cardassia. (DS9: "The Way of the Warrior")
The selection of Federation Council members was one of the tasks that Bajor would have to do if it joined the Federation. (DS9: "Rapture")
The Council were responsible for the decision not to give the Founders the cure to the morphogenic virus. (DS9: "The Dogs of War"}
More Information
For more information, look at Government Structure#Federation Council for non-cannon information.