Snjor - This Program Simulates falling snow all over your screen, and I must at admit it’s rather elegantly done. I installed it on an Aluminium iMac with Leopard and it performs flawlessly. The snow falls from the top of the screen and is semi-transparent, so surprisingly, you can still get some work done. Get Snjor here.
Snowfall Screensaver - If snow on the screen all the time is a little too much for your taste perhaps a snowflake screensaver would be more to your liking? Snowfall is a basic holiday themed screen saver that is easy to install and brings the holiday spirit to any desktop, elegantly. Get Snowfall Here.
X-Mas Tree.app - Want a mini Christmas tree for your computer? Want to decorate it like no other? X-Mas Tree.app has the most elaborate preferences panel for decorating your virtual Christmas tree you could possibly imagine! You can add lights, ornaments, set the trees color, even add a star, popcorn strands, and tinsel!! Did I mention it had a built in countdown till Christmas built in? And if having it on your desktop is too much for you, there is a dock only option. Get X-mas Tree.app
How do you decorate your desktop?