Best small, effective, butt/thigh equipment for at home

I try to get to the gym 4-5 days a week, but with winter's snow/ice, I get stuck at home more than I'd like. I'm looking for a piece of exercise equipment that I can use while I watch tv. It needs to be small, easily storable, and as effective as possible for toning butt and thighs (my main problem areas). Any suggestions? I'm considering this: http://www.amazon.com/Sunny-Health-Fitness-Twister-Stepper/dp/B0016BUR7I but am open to other ideas!