Use a Low Temperature Hot Glue Gun to Make Snowflakes on your Windows! I would make the snowflakes on wax paper first so you don't ruin the window.
Puffy Paint Window Decorations -- Tape down stencil, tape wax paper over top (so nothing moves around), trace stencil with puff paint onto wax paper, let dry, peel off and stick on window!
Hand Crochet Christmas Ornament Santa Ornament by longvalleybears
Graham Crackers instead of Ginger Bread Houses! Mini graham cracker house for Christmas =]