For the Derpiboori 2012 Hearth's Warming contest.
Derpy asked me to forward this letter to everypony and that she's sorry she hasn't appeared much in season 3:
Dear my friends in Ponyville,
It's been a while since I've seen
everypony. Don't worry though, I'm fine!
The Doctor <3 and I have been time
travelling a lot lately in his blue box that
is smaller on the outside! We've been so
busy saving Equestria (and other places too)
from daleks, cyber ponies, and underwater
tiger ninjas that I guess I forgot to
stop and say hi... Last week we went to Victorian
Angle Land and stopped some scary snowponies
from space from eating these hairless pink
monkeys called "hyumins", just in time for
the holidays too! I hope everypony got lots
of muffins for Hearth's Warming!
Your pony pal,
P.S. Go bronies! Woohoo!!
For the convenience of those who would like a full size version of the photograph's image: [link]