It was not really a whiteboard exercise, but I once had an interview at which we went through some of my previous work (code-ish) on a whiteboard. I was mostly

It was not really a whiteboard exercise, but I once had an interview at which we went through some of my previous work (code-ish) on a whiteboard. I was mostly for structure, and I think that's a good example. Also there was a good relaxed atmosphere, so it was more a point of discussion. Got an offer.