Where do story ideas come from?

It seems to be a staple question on almost every interview I've done - where do you get your ideas?

I honestly cannot say specifically what fuels my imagination for stories and novels. Most often ideas come unbidden, when I'm not even looking for inspiration. I'll be thinking about something unrelated to writing and realize it could make a viable story, or I'll be tinkering with some story possibility that's not really working and a solution or better alternative just suddenly sticks its neck out.

I know that if I deliberately set out to come up with what to write about next, I'll get nowhere. This doesn't apply to assignment-driving writing, of course; I'm talking about my own creative endeavors where anything goes. I guess my muse is a like quantum particle. If I try to look at her directly, she disappears. If I ignore her and don't think about writing, she slips something into my brain pan, like she did last night when I wondered what my next novel would be about. I should learn to trust her more. ;D