The kids added two more stars to their winter activities list this weekend: build cars for a drive-in movie and watch a drive-in movie.
I grabbed some large boxes last time we were at Costco and the kids spend a morning decorating them to look like cars complete with paper plate steering wheels, headlights and personalized license plates on the bumpers. I hit Walgreens and bought some candy for the concession stand in the kitchen and we rented a Disney Fairy movie they hadn't seen yet. It was a hit and a perfect way to spend a day when it's below zero outside!
If you're not a member of a superstore like Costo you could always call ahead to a furniture store and ask for them to set aside some large boxes for you. And why stop at cars? Winter is the perfect time to construct a refrigerator-box house!