This is the best snow script I ever seen. It based on XSnow written by Nikolaus Klepp (C)2002 GPL.
So I ported this to wordpress and aded some options.
This plugin can automaticly detect winter and runs scprit only it needed. You do not have manualy activate/disable it.
You can configure flakes quantity, flakes speed.
Download, Activate, Be suprized!
Download Plugin: pti-snow