Desktop Christmas Tree [For Those Who Like That Sort of Thing!]
This is a free exe which runs from wherever it is dropped [no install]
It displays a Christmas tree with twinkling lights etc. You can add more trees with a right click and set tree transparency. A mouseover hint will reveal to you how many days are left till Christmas. [see attached picture]
Download from here: Link
Updated: Desktop Cristmas Tree
I have come across another desktop Christmas Tree:
Link: Christmas Tree
There are multiple skins and three sound files which you can select to play on the hour.
There is a setup program, but once the program is extracted the application seems portable enough to simply copy the files and run from a new location.