A Christmas Carol: Nintendo Wonderland
Although it's far too early for Christmas Carols, this is still a great Nintendo themed carol for the upcoming holidays. Sung by a group of carolers, and probably written by one of their kids, is a song about Nintendo, Mario, Nintendogs and the DS.
Whoever wrote this did a pretty good job.
Update: This seems to have been around for a while, I guess I missed this one. You can find the lyrics for the song here