Marvel sold over $1.6 million retail worth of Amazing Spider-Man #700 to comic stores in December, the top dollar comic in recent memory.  Sell-in of over 200,000 copies was supported by an extensive variant program, including numerous "exceed orders," 1:100, 1:150, 1:200 variants, and at a $7.99 retail price, the dollars piled up fast.  Extensive publicity about the storyline helped make this a major event book.  The lead-in book, #699, appears to have unfilled demand; #698 sold more than #699 (both #698 and #699 have second printings already released).
Marvel also had a big hit with Avengers #1 at over 186,000 copies, but the scale of the dollars wasn’t even close, with less than half the dollars of the #1 book.
The books in DC's "Death of a Family" event were up and down: Batman, for example, was down around 5%, but all of the tie-in titles saw some pretty substantial bumps-- Detective Comics #15 (+31,835), Batman and Robin (+14,335), Batgirl #15 (+2127), Nightwing #15 (+23,687), Teen Titans #15 (+28,962), and Red Hood and the Outlaws #15 (+26,393).  Also of note, DC's Justice League (Part 1 of the "Throne of Atlantis" storyline crossing over with Aquaman) saw an uptick of 2% while Aquaman #15 saw orders increase over 30%.
The Walking Dead Vol. 1 mustered nearly 10,000 sales out of the direct market in December, with gifts of the first volume a great sign for the future of the franchise.

Here are ICv2's estimates of the direct market North American sales of the "Top 25" comics sold through Diamond Comic Distributors in December of 2012:
 
200,966                 Amazing Spider-Man #700
186,989                 Avengers #1 NOW
151,568                 Batman #15 (DOTF)
115,074                 Justice League #15
106,395                 Detective Comics #15 (DOTF)
  93,894                 Avengers #2 NOW
  90,334                 Cable and X-Force #1 NOW
  89,878                 Batman and Robin #15 (DOTF)
  83,798                 All New X-Men #3 NOW
  83,396                 Thunderbolts #1 NOW
  80,665                 All New X-Men #4 NOW
  75,947                 Aquaman #15
  75,341                 Batgirl #15 (DOTF)
  74,904                 Amazing Spider-Man #699
  74,407                 Nightwing #15 (DOTF)
  74,363                 Green Lantern #15
  68,707                 Teen Titans #15 (DOTF)
  66,245                 Amazing Spider-Man #699.1
  64,626                 Avengers Arena #1 NOW
  64,377                 Captain America #2 NOW
  64,103                 Red Hood and the Outlaws #15 (DOTF)
  63,653                 Indestructible Hulk #2 NOW
  61,298                 Action Comics #15
  60,569                 Batman The Dark Knight #15
  60,215                 Deadpool #3 NOW

For an overview and analysis of comic sales in December, see "Spidey Tops $1.6 Million."

For our estimates of actual sales by Diamond U.S. from comic specialty stores on comic books shipped during December, see "Top 300 Comics Actual--December 2012."

For our estimates of actual sales by Diamond U.S. from comic specialty stores on graphic novels shipped during December, see "Top 300 Graphic Novels Actual--December 2012."

For our estimates of actual sales by Diamond U.S. from comic specialty stores on comic books shipped during November, see "Top 300 Comics Actual--November 2012."

For our estimates of actual sales by Diamond U.S. from comic specialty stores on graphic novels shipped during November, see "Top 300 Graphic Novels Actual--November 2012."
 
For an overview and analysis of the best-selling comics and graphic novels in November, see "Marvel NOW! Titles Domiate November Sales."  For an analysis of the dollar trends in October, see "Comics Down in November."