Pointing toes inward or outward is good way way to mess up your knees as leg extensions are open kinetic movements. Even with straight legs, heavy leg ext / curls tend to mess up your knees.
Like Maxelly said abd/adductor machines.
close stance squats hit the outer thigh a lot
wide stance leg presses put more emphasis on inner thigh
Besides leg curls Be sure to include some stiff legged deadlifts for the hamstrings
I think girls can especially benefit from doing heavy barbell lunges as it gives nices seperation (viewed from the side) between quads and hams. Also it builds the shapes the lower glutes in a way that attract a lot of attention from the oppsosite sex....