I'm gonna go on a limb here: The kid who got his father and mother killed during the Wildling raid and escaped to Castle Black is the one who's gonna snipe Ygritte with a bow or a crossbow. The way they show him looking at her while he's under the cart was way too ominous. It also would make sense the Night's Watch would arm him if he can hold a weapon. Of course that's pure speculation, but I wouldn't be against it since it would be a sort of revenge for a poor orphan kid. It would be better than her dying from an unknown archer.
