I'll throw my hat in the ring as I have a folder of Christmas apps. I'll mention only the one not listed already.
"Let's Create Christmas"-allows you to create virtual ornaments
"JL Advent Calendar 2011:- hasn't been updated but still works as an advent calendar. Has a great St. Ives feel to it
"Xmas Radio"-a christmas radio app
"A Christmas Carol by Padworxs"-an awesome abridged version of the classic which has a Steam punk vibe and is interactive.
"WDW Christmas Photo A Day"- Great for Walt Disney world Christmas Photos.
I'm constantly looking for more so I will update as I find them.