I used a method called freestyle training, which is essentially working your legs a little bit every day (kind of 'overtraining' them). It's the principle behind Slim Series and Slim in 6.
You could use something like Tamilee Webb's I want those Buns (there are 3 10-minute workouts), and rotate them each day.
If you can jog, that also works the legs really well.
Callanetics also slimmed my legs a lot...but it's boring, to me.