A catcher, in full gear, squats in a ready to receive position. Five people stand about 35-45 feet away, spread evenly across about a 65° arc. In turn, each person throws a ball at the squatting catcher. The catcher's job is to properly receive the ball, frame it, and drop it. As the catcher is beginning to drop the first ball, the second person should be in the motion of throwing the second ball. Done properly, this drill teaches soft, quick hands.
Have each of the five players throw five balls each. Twenty-five receptions in the span of about a minute will certainly teach soft hands. As age and skill levels increase, you can increase both the number of balls thrown at a catcher, and the pace at which each player makes their throw.