January-
Capt. Jack/Capt. John (both with guns)
Gwen/John/Tosh (all with guns drawn)
February-
Tosh
Tosh/Tosh&Tommy/Tosh
March-
Martha
Martha doing autopsy/Group shot including Martha/Martha entering hub with Ianto behind her.
April-
Jack
Jack & Gwen in foreground with slightly fuzzy Rhys in background and what I think is Ianto, mostly obscured by Gwen's head/Blowfish/Group shot with Rhys, but no Jack.
May-
Rhys/Gwen
Owen with big gun and possibly back of Ianto/space whale/Owen and Ianto with guns
June-
Ianto
Ianto keeping Jack from shooting Lisa/Ianto with hand on Jack's chest from Fragments/Ianto with wedding dress.
Centerfold-
Group shot
July-
Rhys
Rhys and Gwen/Rhys with gun to his head/Jack
August-
Owen
Three different pictures from A Day in the Death.
September-
Gwen and her Dad from Something Borrowed
Jack, Tosh & Owen watching Gwen's wedding/Rhys' mom in close up/Rhys
October-
Gwen in leather
I think a picture of Jonah's bunker room in Adrift/Jonah/Jonah's mother
November-
Jack/Gray
Gray killing Jack/Gray/Gray in the drawer
December-
Group shot
Owen/dying Tosh/Threesome shot of Gwen/Jack/Ianto from the end of Exit Wounds.
Read tea-leaves as you will.