Other than squats I don't do too much with my legs...they really are the highlight of my leg workouts. I'll do leg extensions and prone leg curls and sometimes calf raises...
Last workout I made the mistake of adding lunges into my workout, and that coupled with the squats rendered me nearly *crippled* for about 4 days! I know they say no-pain-no-gain, but when renting a wheelchair almost becomes a weekly necessity, then you know you've gone too far.