Interview: What's your biggest weakness?

Have you ever been asked about your weakness/es in an interview? How did you answer? Did you blab something meaningless about paying too much attention to detail, say with a completely straight face that you don't have any, or did you laugh and say you have a weakness for Belgian chocolate?

This article in CNN's Money column presents some advice on the subject, which is promptly castigated as "exceptionally bad advice" by Mark and Mike at Manager Tools. I can't wait to hear what they have to say on the subject.