I've had a few friends ask me about yoga lately, and I can't recommend Yoga Today enough. Right now, it is almost impossible for me to get to a gym and this is my solution for now. I'm not one for doing tv workouts, since they are usually disappointing and cheesy, but these yoga classes are fantastic! The site provides one free class per week, and this week is a perfect workout for yoga first-timers (note--it might not provide great physical challenge, it is excellent instruction for yoga practice). I also love the beautiful places they film the classes. The Tetons and Arizona deserts are much more calming than a gym.
So, please tell me friends, what do you do for exercise in the winter with kids?