There's a survey you can take at www.keepingsecrets.org. We all keep secrets and here are some that we keep by category according to researcher Michael Slepian.
I'm in the business of keeping secrets and I have mixed feelings about it. The secrets I keep tend to be like nuclear codes, except harmless. There is a feeling about magic — which I think is correct — is that if you saw the sausage being made, you wouldn't want to eat it. So the secrets of how magic tricks work are best preserved, not for any special traditional reason, but for the benefit of the audience. But they remain available for those willing to actually do the research: to wade through the large body of literature we have assembled over the past century and a half. Our secrets remain hidden in plain sight.