Tow strap could help you some day. You could need pulled from a ditch and someone that stops to help might not have one.
A (dangerous) method to use a tow strap to get a single car unstuck is to get it stretched tight between the car and something like a tree, then while one person sits in the car spinning the wheels the other jumps up and down on the tow strap. If you have a decent length strap you get a lot of leverage. Yes its quite dangerous but choosing between your kids freezing to death in the car or doing a dangerous unstick it might be worth it.
Also if you can get the strap under a wheel then tied to something you can use it for traction.