An interesting bit of trivia about Irving Berlin:

While not known as a virtuoso, many considered Irving Berlin to be a fine pianist and he had several performances during his career, both informal and at Hollywood industry functions.

It was a well-kept secret among his family, friends, and close associates that he could only play in one key: F# Major. Everything he composed was in F# as he wrote at the keyboard and then had be transposed in to an appropriate key.

I found this to be quite amusing.