I forgot to describe the schematics. I don't have any schematics atm, will post that later if requested.
Morse input is either via a push button on digital input 7, or audio input on analog input 0. This is just an electret microphone and a one-transitor preamplifier I strung together.
The output is a LED and also audible via a piezo transducer, both on digital output 13.
The piezo transducer needs a signal of some frequency as it doesn't make sounds itself. I just made a oscillator out from an old 74LS13 I had lying around. It's a dual 4-input NAND (Schmitt trigger), controlled by the Arduino. It's the IC and stuff seen in the middle of the breadboard.
Also there is a serial interface to a computer (well, two computers, one for each), showing decoded and encoded Morse, and also for controlling some settings like speed and audio threshold.