I take my puck bag that is big enough to fit over my goalies helmet and have a coach shoot soft shots to the goalie's stick. The goalie's job is to feel the puck hit the stick, then react to clear it left or right on command. The purpose of this drill is to condition the goalie to react to the "feel" of a shot and not the sight. How many times have you seen a young goalie (mite and squirt age) swipe at a puck only to slide in under the pads?
One bonus tip: All players like to practice a "shoot out drill" on the goalie... try reversing it. Let the goalie (or goalies) have a shoot out with the other players. This conditions the goalies to use their sticks with skill and accuracty and gives them some fun skating practice that most goalies do not receive.