If you are using Linux/BSD, and you wanted to have a Christmas themes for your Gnome desktop, here are 2 themes you may download.

I found these 2 themes from http://gnome-look.org.

Ultimate Edition Xmas Theme

This theme pack will not set squat for you. You will have to set the theme etc.
Included in the deb:

1 GTK / Metacity theme
2 Emerald themes
1 Icon set
1 Wallpaper
1 GDM (Jaunty or less)
1 Cursor set
1 Compiz cube cap
1 XSplash (optional & separate package)

Should you decide to install the xsplash (Karmic+ users only) it will replace your current xsplash. If you are unhappy with the xsplash you can replace it by entering the following in a terminal:

sudo apt-get install ubuntu-xsplash-artwork

Download Files:
(Ultimate Edition Xmas Theme Pack)
(Xmas XSplash 2009 Karmic+ only)

Go to the next page for the other theme downloads.