I saw an article about this program on Lifehacker today. It is pretty cool. It is a stripped-down Photoshop, basically, and it is free.

Check out the Symmetry tool. You draw, and it duplicates the strokes in other sextants (6 zones). Easy snowflakes! You can change the 6 to some other number, too.

The quality of the curves was not great for me, but it's free, so I can't complain much.

Here's a link: http://www.sumo.fi/products/sumopaint/index.php?id=0