For my departmental Christmas card this year, I built this Snowflake generator. It goes off to the Adobe Kuler API, searches for 60 color palettes tagged with the word "Christmas" and then generates a little snowflake, based on some patterns that designer Leigh Furby created for me. There's a function to lock the palette, and one to download a JPG of the image, once you've found one you like.

You can play with it live here: http://www.skycreative.tv/Christmas/card/