This teacher had students do a coordinate graphing picture of either a tree or a fireplace for extra credit.
In addition there is a decorating contest for anyone who wants to win a free assignment pass. The students who want to be in the contest color there pictures and bling them out however they choose. The students who want the extra credit, but don't want to be in the contest, just do the coordinate graphing (the kids who do the contest also get the extra credit).
Here are some of the decorated trees and fireplaces that were decorated for the contest:
There are some awesome other Math Holiday activities here including snowflake making.