For the past few years, I have been the glad recipient of postings from Santastic. Although the mashup genre may not be your bag, it certainly seems to fit the theme of "modern holiday".
Granted, most music is built on "the shoulders of others" (Isaac Newton), but the Mashup genre brings the style to the fore: take a collection of other people's songs and mash them together to create something new. This is a topic I covered at least once in my own (sadly neglected) blog >> see the right side list, but the subject of mashups deserves a re-visit at this time.
My favorite of the collection this year: banabul.com/muzik/fpc.mp3
It's a mashup of "Mr President" and Johnny Cash called Folsom Prison Christmas
[I suspect you will have to right click copy/download the file even though it is Creative Commons]
See this link for much more of this genre:http://www.christmash.com/
