Before I pass you on to the OS X snowfall screensaver you are probably looking for, I wanted to metion another snow-related project of mine you might be interested in.

If you have an iPhone, iPad, or iPod Touch, please have a look at Shorelines, a free download on the iOS App Store. It generates trees and snow, and I think it's rather pretty. You might like it.

Otherwise, please feel free to download Snowfall. It works on OS X 10.4 to 10.6 (sorry, no Lion).

The snowflake images used as a basis for this screensaver were taken by Wilson Bentley, and are in the public domain.