Hamstrings and glutes - deadlifts: standard, sumo, stiff leg and Romanian. Good mornings will also hit the entire posterior chain. Box squats will also hit the hamstrings pretty hard. Learn proper form on ALL of these lifts before trying to add weight and lower the rep range - improper form can injure your lower back. The "ideal" rep range seems to vary with the individual. If your not getting the results you want I would try the 6-8 rep range once you have your form down - you can always change it back or try even higher reps.
"First say to yourself what you would be; and then do what you have to do" - Epictetus