Back on the Dragons vs. Balrogs thread the comment was made that Tolkien's works are totally independent of any other mythology. I thought that it would be more appropriate to post my reply to that here.
I would say yes and no. Yes, Tolkien's writings were his own and different from other myths.
However (and this is just a thought) I think maybe there could be a way of looking at them as being related. Since Tolkien's world is this one in a much earlier stage I think that perhaps you could look at other mythologies as being attempts to recall those days or look at them from another perspective. Thus, the differences are because of distance and interpretation. (Ever wanted to know what the Easterlings thought about things? Maybe we do...)
Yes, I know that this idea is backwards chronologically speaking, but it was just a thought.