Thinking bigger with tiny budgets

I don't need to tell you that a good PR stunt can have a massive impact but when everything seems to have been done, how can you stand out? I had a conversation with a chap at a children's birthday party the other day that went from fairy bread (not kidding) to the discussion of an epic PR stunt across a continent with potentially huge media coverage. So can you as a small team of PRs or even on your own, punch way above your weight and get noticed on a national level without spending a fortune? Could you even get everyone to do it for free?