Today is Festivus, a microminiholidayette made popular in the United States in 1997 by the television sitcom Seinfeld.
Writer Dan O'Keefe invented Festivus to commemorate his first date with his future wife, Deborah, back in 1966. Their son Daniel became a writer on the Seinfeld show and borrowed the idea for a script. The Wikipedia article on the subject suggests that the younger Mr. O'Keefe embellished quite a bit on his father's concept, and what he didn't embellish he made up out of whole cloth.
But you can put up your own aluminum pole today if you wish. We won't laugh at you -- not where you can see us, anyway.
Today is also Roots Day, a day to remember and celebrate and perhaps even explore your origins. At this time of year, as families gather together, what could be more appropriate, right?
Usual Suspect Hallmark suggests that today is National Pfeffernusse Day, pfeffernusse, apparently, being some sort of a German cookie.
According to Wikipedia, the classic Christmas poem "A Visit from St. Nicholas" ('Twas the Night Before Christmas) was first published -- anonymously -- on this date in 1823.