K.F.
You've had several recommendations for dancing, and I totally agree - I just thought I'd throw in after getting a Wii for Christmas (and we like it as much as the kids) we recently got the game "Just Dance". You don't need a special mat or anything, just the regular controller and it is a blast! My girls ask to play it just about every day, and I've been using it for my workout since I can't seem to make it to the gym. It is great for the cold yucky days, and it definitely gets the heart rate up! (and although she doesn't do "well" my 2 year old really enjoys dancing along and participating as well - all 4 of us can play at the same time).