I've just finished A Dance With Dragons and realized that the Red Comet which appeared in the early books had made no appearances lately.
I've been reading the series before going to sleep so I wasn't always at my most alert and may have missed it but I don't remember anyone commenting about the comet disappearing. Since it seemed to be such a big deal for many people I would expect the plot to reflect when it stopped appearing (or if it didn't stop why is nobody noting it as they did in the past?).
Did I miss something?
The smoke and ash clouded his eyes, and in the sky he saw a great winged snake whose roar was a river of flame. He bared his teeth, but then the snake was gone.
Don't know if its the last sighting of the comet (or even if that really is the comet).