This is my off-season leg workout. It is brutal. I do 3 sets of each exercise, around 10-15 reps.

30 minute cardio (I do stationary bike, anything except the treadmill)
STRETCH (very important. Do it thoroughly)
squats
one-legged leg press (man, do these hurt)
one-legged leg extensions
leg curls
abs

You'll barely be able to walk for the next 3 days, but you'll get strong quick.