Ultimate glute builder=SUMO SQUATS.
When squatting,take a wide stance,with your feet pointed as far OUTWARD(away from one-another)as possible.Drop down VERY low(below parallel)on each rep.Start off with very light weights to get command of the movement,your balance,and the feel of the glutes working.After you've mastered those three areas,gradually move up in poundages,and in no time flat you will have glutes that are quite full(as well as strong as hell,which will help in all your power movements requiring lower body strength),muscle-wise.