Both my family and my wife's family had the tradition of opening one present on Christmas Eve.
My family (with my wife and children) also has the tradition of the advent calendars with chocolate inside. Over the past several years, I have also been doing the twelve days of Christmas with booster packs from various CCGs. The first few years were Pokemon, then later came Megaman, Teen Titans, Acceleracers, Bionicles, and finally Kingdom Hearts. I always found the boosters dirt cheap on eBay, since the games were already defunct (except Pokemon, which we simply gave up on). Redemption boosters were part of Christmas Day presents, since they are so much more awesome.
One other tradition from my wife's family (that I found peculiar) was that her father would take them all to Pizza Hut on Christmas Eve. When I joined the family, I joined the tradition. I was used to having baked ham on Christmas Eve, and turkey on Christmas Day. However, I played along with their family's tradition instead.
After my wife's father passed away, the Pizza Hut trip became more sentimental. Yesterday we received a Christmas card from my wife's younger brother, who has just started his own family. Inside the card was a gift card to Pizza Hut. He wanted to make sure that everyone would be in the same place on Christmas Eve, so he sent a gift card out to all the siblings.
