Genesis or Big Bang. How was your world created?

Based on many of the posts here, it seems to me that many people are concerned with how plausible their world is, from plate tectonics to commerce. Yet the strand of world-building inspired by the fantasies of Tolkien draw more on the ideas of magic and mythical creation than science. I find that it would be interesting to explore the idea of creation with all you fine folks to see which way the wind blows these days.