Snowflakes!

A site all about snow crystals and snowflakes -- what they are, where they come from, and just how these remarkably complex and beautiful structures are created, quite literally, out of thin air.
http://www.its.caltech.edu/~atomic/snowcrystals/

Free Printable Snowflake Patterns:
http://www.marcels-kid-crafts.com/snowflake-pattern.html