Have a picnic in the living room. Eat salad and sandwiches on a blanket on the floor. To make a town to play with little people, make buildings out of shoe boxes.
Drape sheets over tables for tents, eat marshmallows, etc.
Have a paper plane throwing contest - see who can decorate it the best and who can throw it the farthest. Fill empty diaper bags with newspaper and tape closed for large, soft building blocks for toddlers. Save egg cartons for kid's paint trays or canvas. Fill squirt bottles with water and food coloring and send your kids to go paint on the snow. Make a family tree by having your kids gather branches and leaves.