Well, I personally love Christmas time at my sorority. We go all out with decorating the house. We have tons of lights outside (all white lights) around the pillars, in the bushes, candles in the window, wreath on the front doors and we put up a Christmas tree in the formal. It's a lot of fun and Evan's Scholars has a philanthropy where they judge all of the houses on their outdoor decorations. We won last year and hopefully we will again this year!
Last year I also organized a Secret Sigma gift exchange, which is basically Secret Santa. A bunch of people sign up and I distribute names to everyone and they buy for the person they were given. $15 maximum. It was a lot of fun and we got together one night during finals week and exchanged around the Christmas tree.