Dreaming of a Plot

I was thinking about how writers come up with their stories, plots, ideas, etc.
A lot of my ideas originate from dreams. I have really vivid and extremely detailed dreams, some bordering on exceedingly odd. So, I write what I dream, and bring it to the light of day... well... the edge of reality as far as my screen and paper can take it at this time. A couple friend's commented that they have also written a lot starting with a dream that spawned an entire reality. My current work in progress actually came into being starting with a very sleepy drive to work. My mind was wandering, luckily the roads were clear that particular morning, and I it just came to me - as if in a dream. I was hooked on the idea, and just let it blossom from there.
So, how do you get your ideas? What is your muse?