I posted a tip on tuning without an electronic tuner a while back but I always need an A440 reference to start with. I don't know how close I could come with out a tuning fork but I'm guessing not very.

When I was seven or eight years old, my parents used to make me turn my back while one of them played a note on the piano. I was expected to correctly identify the note. I'd play along and try to guess but I don't remember ever being reliably consistant at the game.

      - Mark