A button on the Production page of the Barracks and Consulate (and other buildings that produce more than one item) that allows you to build multiple types in one click. At the moment, for example, if I lose 5 Phalanxes, 5 Wardancers and 5 Trueshots in a battle, I have type in the number three times and click build three times for each unit type. 

A button at the bottom of the page that builds all types of units you have entered a number for in a single click would be lovely, this would be a Prestige only button too as you obviously cannot have more than one type building on a non-Prestige account. :)