Thanks Tim. I, too, hadn't found anything that worked well. Usually, the filler wouldn't take the stain so it would crack and come up. Depending on one's definition of gouge, I would opt to sand or replace the board. Certainly, there are tricks to get a relatively new board from, say a closet, to look like a 'worn' one.
And as for our Poster, if you need to replace the board, I'd hire a pro. Once you're in the house, the floor is your calling card.