#1 son and I had a great time at the Manchester Raspberry Pi Jam at Madlab on Saturday. We got the Pi up and running and making an LED flash morse code out. Turns out you've got to worry about the length of the gaps just as much as the length of the flashes.
Here's a video of the Pi saying 'Hi Mum'. I promise it is the Pi doing the work and not the laptop.
The plan for next time is to make a bright enough light source that another board connected to a Pi can read the Morse Code back in using a photo-resistor.