If you're like me, you like to see the pins in a tumbler as the key slides into the barrel of the lock. No, that's not a sexual innuendo. It's just plain cool to see the inner workings of a complex machine.
There's just such a thing for crypto enthusiasts in the form of a virtual Lorenz machine. Here is the link, courtesy of CptDateGrape on IRC: http://www.lorenz.virtualcolossus.co.uk/LorenzSZ/
More info on the Lorenz cipher here: https://en.wikipedia.org/wiki/Lorenz_cipher