Wow! I had no idea that Tom was such a huge topic of discussion.
I am glad that I am not the only one who has wondered who and what Tom might be. After having read all five pages of this thread, I am inclined to think that he is some kind of earth spirit, if anything. Discussing him is fun. I wish I knew what Tolkien was thinking when he put Tom in the books.
Probably something like, "Mwahaha, now I can plague the minds of all my readers with incessant curiosity and wonder as to who this character is..."
Now I am convinced. Tolkien was an evil genius.