Writing Prompts? Love 'em or hate 'em?

I'll be honest - I am NOT a fan of "writing prompts" - they were used by several of my professors at Harvard, and at first I was tempted to write them off as laziness - a way to get the students to shut up and scribble away (or in my case, stare at the wall) for a few minutes so the professor could get their notes together. But I saw that some of my favorite professors - great authors in their own right - used prompts too. And that some of my classmates really responded well to them. And one day, in a class on short short stories, one of those prompts just... worked. I'm still not a big fan - but I have gotten at least ONE great story - and one great character - out of a "writing prompt" exercise. So, that's my story - what's yours?