I like to use powdered milk as part of a dredge for breading fried foods. Instead of dipping the meat or vegetable into liquid milk and then into flour, I will sometimes dip it into powdered milk first, then into an egg wash, then into the flour or breadcrumbs. I think it adds a layer of creaminess to the finished product.
The other thing I'll do with powdered milk is create emergency meals for the homeless. I'll buy a can of dry diet shake mix, some powdered milk and resealable plastic baggies. I'll measure one scoop of the diet powder and two scoops of the powdered milk into the baggy and seal it. I will later place the baggies into disposable cups along with a plastic spoon.
The recipients can decide when they want to have a nutritious replacement meal by mixing fresh water with the powder mix in a cup. It may not sound appealing, but the emergency meal does contain essential vitamins and minerals.