Wouldn't Tom have noticed?
 

O.k., I was reading in Unfinished tales, around pg 451:

My question is, if the captain of the nazgul were near the barrow downs, wouldn't Tom have noticed? I meen, when Frodo sang, he could hear him, so why not when the barow wights woke up? Any ideas?

Well, Tom probably did notice, but he seems to be unwilling to take action unless someone is in peril. He could have opened all the barrows and destroyed all the wraiths if he wished, but he only destroyed those attacking Frodo and Company. I think Tom only attacked or otherwise interfered with the affairs of ME if he felt someone was in danger. Remember the council of Elrond, where they say that Tom would not take the Ring, unless all the free people of the world begged him to. He seems to be rather unconcerned with anything that happens that doesn't directly interfere with him.

I argee Daniel, Bombadil would help some one IF they were in his little area. it might also have some thing to do with the fact that Frodo sang the song that Tom taught him he didn't just yell for help like there's no tommorow maybe the song was magical?

Another possibility is that Tom did not inhabit that section of forest until after the witch king had left. Does anyone know when Tom moved to those parts? Elrond did not know that he still existed, and it seems that he would have heard somehow if Tom had been around for 1000's of years.

By around I mean in the same spot. I know he is as old as the hills etc.