Spoonful has a really inventive way for kids to make their own snowflake window accessories using wax paper and puffy fabric paint. They even provide a template but also show you how to create more of your own.
Good for ages 7 and up.
Get the instructions here:
http://spoonful.com/crafts/glittery-window-clings
Get the instructions here:
http://kidsactivitiesblog.com/49213/snowflake-coloring-pages