I just thought of some great "D" names if the little monster shows up early.
Dasher (reindeer obviously)
Dudley (from Christmas in Connecticut)
Douglas (for the Douglas Pine)
Dove (perhaps a bit girly)
If he's a new year's baby:
Dagny (means new ay)
And if he is born December 29th or 30th:
David (apparently its traditional names for the day in religious or traditional calenders in many countries including France for the 29th)
Of course if we throw off family tradition since Daniel isn't the first born (and technically not part of the tradition) there are many more options. Who wouldn't want a kid named Claus.