What are the most interesting equivalences arising from the Curry-Howard Isomorphism?

Question

I came upon the Curry-Howard Isomorphism relatively late in my programming life, and perhaps this contributes to my being utterly fascinated by it. It implies that for every pro

Answer 1

First-class continuations support allows you to express $P \lor \neg P$. The trick is based on the fact that not calling the continuation and exiting with some expression is equivalent to calling the continuation with that same expression.

For more detailed view please see: http://www.cs.cmu.edu/~rwh/courses/logic/www-old/handouts/callcc.pdf