The front squat is a beast of a move, and is also surprising easier on the lower joints than the traditional squat. it equally helps with balance, strength, and building endurance and flexibility. FRONT SQUATS FOR EVERYONE!
Lunges ~ one of the most effective lower body moves you can do. If you are trying to build strength in the legs or mass in the legs, increase flexibility in your knees, or build that booty -- lunges are for you ;