I suspect (and hope) you've probably revealed yourselves by now and archived your stories, but if you haven't then please feel free to do so! If you post on Ao3, Santa's House Elf would be grateful if you would add your story to the HP Holidaygen 2013 collection.
alley_skywalker wrote Last Look Back Before You Jump for jokerofish
chthonya wrote When Snape Stole Christmas for primeideal
delphipsmith wrote Guess Who's Coming to Dinner for thornyrose42
flaminia_x wrote You can call me Al for snorkackcatcher
hikarievandar wrote Masquerade: The Last Yuletide of Regulus Black for alley_skywalker
lazy_neutrino wrote Doorways for delphipsmith
lyras wrote A Reason to Fight for lazy_neutrino
lyras wrote The Friends That Cannot Sup With Us for fpb
primeideal wrote The Yeoman's Yuletide for flaminia_x
thornyrose42 wrote Held by the Thorns for hikarievandar
snorkackcatcher wrote The Strong Box for chthonya
(I am deeply sorry about the l o n g delay in posting this. I don't want to go into detail here because this is about the stories not my weaknesses - I got ill, basically, and didn't deal well with the aftermath. There's more here for anyone who wants a fuller explanation. PM me (chthonya) if you can't see it and you want to.)
ETA: The fest will run again in 2016, with two mods and lots of lovely new canon to explore! More soon - look out for sign-ups around the start of September.