Snjr

First it was Snowfall, then LotsaSnow came to my attention, and now Snjór is the current snow related OS X app that has my eye (thanks to Sveinn). Snjór creates little snow like globes that float down your Mac's screen while you are using it (that is to say that this is not a screensaver, but rather an application that draws these little guys on your screen). You can set how many snowflakes fall, how fast they fall, and if you want them to accumulate on top of the active window (seen above).

Snjór is free and Universal, and the developer (the awesomely named Ninja Kitten) promises that the source will be available on December 24th.