I'm always amazed at the breadth and depth of Feynman's genius. My favorite story of Feynman is his calculation of the size of the first nuclear explosion and then driving to just a few miles outside the blast radius (much closer than his colleagues were willing to watch from). That's a level of mental confidence that I can't even begin to imagine possessing.
Surely You're Joking is a great read - one of those "drop what you're doing and read it now" kinds of books.
My favorite story about estimating yields of nuclear weapons is the confetti method. I recollect it being attributed both to von Neumann and Fermi. I am not sure
who the actual person was.
The way it worked was at the sign of the flash he released torn shreds of paper and noted how far they were dispersed by the shock wave that followed. This mental calculation turned up to be quite accurate.
Surely You're Joking is a great read - one of those "drop what you're doing and read it now" kinds of books.