The ghost of harrenhal escapades actually happened under Tywin’s/Amory Lorch’s rule, though it is a cool parallel.
You know, I really hope that Bran wasn’t speaking to Theon. It seems much better to me that Theon was just standing there in the Stark’s holiest of places, thinking about his life, and the rustling of the leaves (whether blown by Bran or not) sounded to Theon like "Bran" because he was thinking about him. It’s like the comet in ACOK – everyone thought it meant something completely different, and saw in it what they wanted to.
I’m really digging the Stannis/Roose confrontation. I thought that Stannis was in enormous trouble, but seeing that Arnolf would have stabbed him in the back, the snows may actually have saved him and doomed Roose’s alliance – it worked ok when they all have space, but now they’re all bottled up getting cabin fever it’s only a matter of time before a mass brawl breaks out. It was brilliant seeing Roose’s cool exterior crack, even for a moment.
Regarding the drums, is it possible that it’s the northern clansmen? We know they could travel much better in the snows than Stannis’s main troops. If Roose’s men on the battlements can’t even see past the outer wall, they’d have huge problems fending off the northerners if they have the equipment to scale the walls.